A Brief Explanation of the Trinity

James M. Arlandson

What is the doctrine of the Trinity all about, anyway? Why do Christians hold to it? Where does it come from? What does it teach? Why does not Islam teach it? This article addresses these questions and more.

As for Islam, Muhammad promises a painful punishment (i.e. hell) for Christians who believe in the Trinity:

5:73 Those people who say that God is the third of three are defying [the truth]: there is only One God. If they persist in what they are saying, a painful punishment will afflict those who defy [the truth] (MAS Abdel Haleem, The Qur’an, Oxford UP, 2004)

He goes on to say in the context that Jesus was only a human messenger (v. 75). Also, Christians follow the whims of those who have gone astray before them (v. 77). Clearly, Muhammad will not tolerate disagreement with his own doctrine, and he also fails to understand the Trinity in his "third of three" wording. For more information on Muhammad’s verbal confusion in this verse, go here, and scroll down to point no. 3.

Next, Muhammad wishes damnation or puts a curse on Christians for believing that the Messiah is the Son of God:

9:30 [T]he Christians say: "The Messiah is the son of Allah." That is their statement, by their own mouths; they emulate the statement of the unbelievers of yore. May Allah damn [curse] them; how they are perverted. (Majid Fakhry, An Interpretation of the Qur’an, NYUP, 2000, 2004)

This verse follows Muhammad’s declaration of war on the Byzantine Christians (Sura 9:29), against whom he launched his own Crusades to the north, with thirty-thousand jihadists in AD 630. He must make the "perverted" Christians no better than "the unbelievers of yore" or aforetime, who include polytheists. Be that as it may, one of the odd features of Muhammad’s beliefs is his assertion that Jesus is the Messiah. He does not understand the full importance of this title, but he accepts it, even though the New Testament, specifically the Gospel of Matthew, connects the Sonship of Jesus with his Messiahship (Matthew 16:16-17). See this article on Muhammad’s confusion in Sura 9:30.

Once again, these verses show, historically speaking, that Muhammad picked up fragments and scraps of ideas about Christianity, here and there along the trade routes, in a haphazard way. Muhammad did not have a qualified Christian to explain this doctrine to him.

Besides being intolerant, Muhammad, the self-declared and self-described human messenger (Sura 3:144), is confused.

To clarify the doctrine of the Trinity, we follow the format of asking common questions and answering them. Links are also provided so the reader can explore these answers more thoroughly.

1. Where does this doctrine come from?

This doctrine comes from the New Testament with hints from the Old Testament. Four passages represent others.

First, at the baptism of Jesus, the Father, the Son, and the Holy Spirit were present. As soon as Jesus came up out of the water, "he saw the Spirit of God descending like a dove and lighting on him. And a voice from heaven said, ‘This is my Son, whom I love and with him I am well pleased’" (Matt. 3:16-17). The Father’s voice sounded from above and affirmed the Sonship of Jesus, and the Holy Spirit descended on him and empowered him.

Second, at the end of the same Gospel, Jesus is resurrected, and he commissions the disciples to go into all the world and preach the gospel. These two verses are part of the Great Commission, which Evangelicals take seriously. "All authority in heaven and on earth has been given to me. Therefore, go and make disciples of all nations, baptizing them in the name of the Father, the Son, and the Holy Spirit" ... (Matt 28:18-19).

This passage affirms that Jesus was granted all authority in heaven and on earth. This raises him high above a mere prophet. This passage also demonstrates Jesus’ early declaration of the Trinity. Therefore, this doctrine comes from him, originally.

For information on Jesus being granted all authority, see the beginning of this article.

Third, Christians believe that the entire New Testament is inspired. The Apostle Paul also affirms the doctrine of the Trinity. In his second letter to the Corinthians, he bids farewell to them: "May the grace of the Lord Jesus, and the love of God, and the fellowship of the Holy Spirit be with you all" (2 Corinthians 13:14). Thus, Jesus and the Holy Spirit exist with the Father, and from their heavenly vantage point they are able to communicate grace, love, and fellowship to the believers (cf. Ephesians 4:4-6).

Fourth, Peter the Apostle, the humble fisherman from Galilee, stood in Jesus’ presence when he spoke the Great Commission. Peter may not have fully understood Christ’s words then, but now he begins his epistle, under the inspiration of the Holy Spirit, restating the Trinitarian formula in his own words. He says that the people of God "have been chosen according to the foreknowledge of God the Father, through the sanctifying work of the Spirit, for obedience to Jesus Christ and sprinkling by his blood" (1 Peter 1:2). It is clear from this verse that each person of the Trinity has a function or role in the world. The Father chooses, the Spirit sanctifies, and Jesus redeems people with his blood that he shed on the cross.

To sum up, the doctrine of the Trinity was first stated in the Gospel of Matthew, both at the baptism of Jesus and in his Great Commission, in his own words. It is only natural, therefore, that the apostles would repeat his doctrine.

The readers should go to here and look up these verses: John 1:1-4, 14:26, 15:26, 16:13-14, 20:25-27; Acts 10:38 in connection with Romans 9:5, 15:13; 1 Corinthians 12:4-6; Colossians 2:9; Hebrews 1:3, 1:8, 1:10; Titus 2:13; 2 Peter 1:1; Jude 20-21. Each passage affirms the function and person of the Father, the Son, and the Holy Spirit, and sometimes just the Father and the Son.

This site has a list of other verses, including from both the Old and New Testaments. This page at the same site lists references to Christ’s divinity.

2. Doesn’t this doctrine really come from later Church fathers?

This doctrine is developed by great theologians like Athanasius (c. AD 296-373) and Augustine (AD 354-430), but it was not invented by them. The New Testament was written to clarify pressing doctrinal and pastoral problems and issues that arose in the church. Here are four examples: what did Jesus teach or do about sickness or dietary laws or the Sabbath? What was his resurrection like (cf. the four Gospels)? How are people saved (or get into heaven) and are sanctified by the Holy Spirit (Epistle to the Romans)? Why should Christians not subject themselves to an old-new law (Epistle to the Galatians)? And how should Christians live in the church and withstand persecution (Peter’s Epistle)?

Therefore, the New Testament authors, under the inspiration of the Holy Spirit, were not directed to develop the doctrine of the Trinity. Instead, they seemed to have assumed it, as we saw under point no. 1, and the four passages. They affirmed the full deity of Christ and the full deity and personhood of the Holy Spirit.

To repeat, Church fathers developed the doctrine of the Trinity from their reading of the New Testament, but they did not invent the doctrine out of thin air. For more information on the doctrine in the church fathers (post-apostolic church), see this site.

3. Is the word "Trinity" found in the Bible?

It is not found in the Bible, probably for the reason stated in no. 2. The New Testament authors were engaged in other issues, and they assumed the reality of the Trinity, which is greater than a label. Besides, the word "tauhid" or "tawhid" or "oneness" is not found in the Quran, but Muhammad preaches this doctrine in other ways.

For more information on the absence of "tawhid" in the Quran, go to this article, and scroll down to the large letters in blue font.

4. What does this doctrine teach?

This doctrine teaches that God exists in three persons who share the same essence or being. What this means is that God exists in the distinct and co-equal persons of the Father, the Son, and the Holy Spirit, but they share a fully divine essence or being, such as uncreatedness, eternality, simplicity (non-composite or indivisible), immutability (unchangeableness), omniscience (all wise and knowing), omnipotence (all powerful), goodness, mercy, holiness, will and freedom, and so on.

Thus, in God, the attributes of his essence are fully shared by three persons, making each person fully God.

Yet, the three persons are distinct. The Father is neither the Son nor the Holy Spirit; the Son is neither the Father nor the Holy Spirit; and the Holy Spirit is neither the Father nor the Son.

But, to repeat, the three persons share the same essence. That is, the Father and Son and Holy Spirit duplicate the same attributes. The Father, the Son, and the Holy Spirit are equally wise and merciful and holy; one is not more wise or merciful or holy than the other. Augustine says: "These three have the same eternal nature, the same unchangeableness, the same majesty, the same power" (On Christian Teaching I.12).

This site has a list of the divine attributes that all three persons of the Trinity share in perfect unity; click on any of the pages. This page at the same site also references verses in the Bible concerning the divine attributes.

5. How are the three persons distinct?

They are distinct in their relationship with each other and in their function or role in creation and in the plan of redemption and salvation.

In the work of creation, the three persons of the Father, the Son, and the Holy Spirit had different functions. God the Father spoke the world into existence (Genesis 1-3), but God the Son carried out the divine decree. The Gospel of John says of Jesus: "All things were made through him [Jesus], and without him was not anything made that was made" (John 1:3). God the Holy Spirit was active in creation, "brooding over the face of the waters" (Genesis 1:2; see also Psalm 33:6 and 139:7).

In the work of redemption and salvation, the three persons have different roles or functions. God the Father planned the redemption and sent God the Son into the world to carry out the plan of redemption. He obeyed the Father and died on the cross for our sins. Neither the Father nor the God the Holy Spirit carried out this part of redemption. The Holy Spirit was sent by the Father and the Son (John 14:26 and 16:7) to apply the plan of redemption to the heart of each person who receives it. The Holy Spirit also purifies and sanctifies us or makes us holy in our daily lives.

In relation to each other, we see that in the creation and redemption, the Father sends and directs the Son (Ephesians 3:14-15), who obeys and goes where he is directed, revealing the full nature of God the Father to us (John 1:1-5, 14, 18; 17:4; Philippians 2:5-11). These roles fit perfectly with Fatherhood and Sonship. Both the Father and the Son send the Holy Spirit, so the Spirit obeys both the first and second persons of the Trinity.

Thus, while the three persons of the Trinity have and share the same attributes (holiness, mercy, omniscience, and so on), they have distinct roles or functions as they relate to each other, to creation, and in the plan of redemption and salvation. They are equal to each other in their divine attributes, but the Son and the Spirit are subordinate in their roles.

For more on these ideas, see Wayne Grudem, Systematic Theology, Inter-varsity Press (UK) and Zondervan (US), 2000.

6. If there are three persons, why are there not three Gods?

The co-equal and distinct persons of the Father, the Son, and the Holy Spirit are not three Gods because they share the same essence in complete unity. This is difficult to grasp because we have no comparison that we can experience empirically or with our five senses.

For example, the patriarchs Abraham, Isaac, and Jacob are three distinct persons and beings. They do not share the same essence or being or divine attributes. However, the doctrine of the Trinity says that the Father, the Son, and the Holy Spirit share the same being or essence, and this is where the human example of the three patriarchs and the divine nature must part company. So the human analogy fails to describe the Trinity and would in fact confuse this doctrine if we took the example seriously.

Augustine comes up with an analogy that is deep: the lover, the beloved, and love (The Trinity, Books VIII.14; IX.2, and XV.10). As we saw at the baptism of Jesus, the Father says that he loves the Son, and at that very moment, the Spirit descends and rests on Jesus (see no. 1, above, and Matt. 3:16-17). Augustine seems to say that the Father loves the Son, who receives his love and returns it, for example, in his willingness to obey the Father and die on the cross, while the Spirit communicates the love between them. This image of a triad of love expresses how Christians believe the Father, the Son, and the Holy Spirit existed before the creation of time and the universe, and how the three persons will forever exist. It is into this love that the Trinity welcomes all believers and all who have received the love of God, through Christ and by the power of the Holy Spirit.

Augustine’s analogy is profound, because we have all experienced love from a lover, and we have returned the same love. But it still does not adequately explain how the one God shares this divine attribute of love and all the other divine attributes in three persons. Our human love is but a poor reflection of divine love. We cannot observe this with our eyes, so all analogies from nature and humanity ultimately fail in illustrating the Trinity. Analogies from nature cannot reach up to heaven so that we can connect them to the Trinity. Our finite and limited mind cannot grasp this mystery, even after our minds have studied the doctrine for years.

This page discusses the philosophical necessity of the Trinity, based on Augustine’s analogy of divine love. The strict unity of God does not make sense in terms of the love of God, because divine love amounts to self-love in a strict oneness doctrine of God.

To clarify further why there are three persons, but not three Gods, God’s essence is not divided equally into three parts; it is not one-third, plus one-third, plus one-third. Also, the three persons are not added on to God’s essence or being, as if they are tacked on to the outside of God. Rather, all three persons share the same essence, fully God in one being, in total and perfect unity.

Thus, basic Christian doctrine teaches that one God exists in three persons: the Father, the Son, and the Holy Spirit, not in three Gods, which is called tritheism.

Besides giving a list of divine attributes, this website uses some properties of creation and this series presents a mathematical model to illustrate the Trinity, though, as noted, all analogies are ultimately flawed.

7. However, doesn’t 1 + 1 + 1 = 3? So isn’t belief in the Trinity irrational?

The previous section just asserted that all natural analogies fail, and so do mathematical ones. However, since these questions reflect Muslim polemics against this doctrine (a Muslim emailer wrote this to me), we should get into the mathematical arena and answer them.

First, multiplication works better with integers:

1 x 1 x 1 = 1.

Second, the exponent comes out the same:

13 = 1

Third, how about an infinite number of sets of things? This works better:

Infinity + infinity + infinity = infinity.

Let us say that we add an infinite number of red books to an infinite number of white books, and still add an infinite number of blue books to the red and white books. Despite adding these three sets of infinite numbers of books together, we have not augmented or increased infinity by even one book. Such is the mystery of infinity; we cannot figure it out.

However, these three mathematical analogies of the Trinity ultimately fail because, among other reasons, the three infinite sets of books have different properties, because they do not exist in perfect unity in one essence, and because we do not "add up" or even "multiply" the three persons of the Trinity.

But the infinity analogy does reveal the utter mystery of things that we have never experienced with our five senses. And we have never experienced an actual infinite number of things. Even time is finite, since the so-called Big Bang, which states scientifically that the universe has a beginning.

Thus, infinity is a mystery, and so is the Trinity. Belief in the Trinity is not irrational, but transrational—above our puny minds to figure out, ultimately.

8. Doesn’t the doctrine of the Trinity entail contradictions?

Mysteries are not contradictions. Here are two examples of contradictions: there is one God and there is not one God; or God is three persons and God is not three persons. But the claim that the one God exists in three persons who share the same divine essence in perfect unity does not entail a contradiction (Grudem, p. 256).

The Trinity ultimately is a mystery, but it is revealed in scripture, so all Bible-educated and Bible-believing Christians believe in it, even though they may not understand it fully.

This page explains more fully why it is not a contradiction to say that three persons share the same divine essence.

9. Still, though, would the true God exist in a complicated way like the Trinity?

We Christians believe that God is knowable as far as he has revealed himself through Jesus Christ, the Scriptures, and the Holy Spirit who lives in us, and other avenues like the creation. However, we also believe that God in his pure essence is unknowable. No one has seen God in all of his splendor and glory. We humans down here on earth are limited by our five senses and our finite minds, which process the data taken in by our five senses and somehow reformulate them into ideas. For centuries philosophers have been debating each other over how the mind works. So how can the human mind figure out and calculate the pure nature of God? Given God’s infinite greatness and ultimate unknowability, and given the finiteness of our five senses and the limits of our minds, it stands to reason, therefore, that some ideas about God are perplexing and unsolvable.

C. S. Lewis alludes to this in his book Mere Christianity, in the chapter "The Invasion" which discusses the Incarnation (God the Son becoming man). Here he does not accept the natural human wish that religion should be simple.

It is no good asking for a simple religion. After all, real things are not simple. They look simple, but they are not. The table I am sitting at looks simple: but ask a scientist to tell you what it is really made of—all about atoms and how the light waves rebound from them and hit my eye and what they do to the optic nerve and what it does to my brain—and, of course, you find that what we call "seeing a table" lands in mysteries and complications which you can hardly get to the end of.

Lewis uses the example of looking at a table, and if we let our vision go no further, then the table remains simple, but if we go down the path of knowledge any farther, then the table gets complicated really quickly. The same is true of our knowledge of God. If we keep our knowledge of him simple, then we are not bothered by the deeper doctrines. But once we probe more deeply, we discover that God is ultimately a mystery in his pure essence and glory.

Personally, one reason (among many) that I believe in the Trinity is precisely because this doctrine is ultimately beyond my puny brain to figure out. I could never have invented it. God in his pure essence cannot be known by me. He is beyond my five senses and my brain power, so it is logical that some ideas about him are difficult to understand.

For a great article on how the incomprehensibility of God (Deus absconditus) is a necessary criterion for establishing a true religion, go here. This article also discusses what the mystery of God means to us humans, with many biblical references. Finally, this article reinforces the idea that God is not simple.

10. Doesn’t the doctrine of the Trinity ultimately come from pagan myths?

The doctrine of the Trinity, if properly understood, is found nowhere in mythology—not even close. Zeus, Poseidon, and Apollo, for instance, and any other trio of gods from around the world do not share all of the same attributes in perfect unity as one God. In fact, Greek myths go out of their way to keep these gods distinct as three gods and beings with their own special attributes. The Trinity has nothing to do with a family or pantheon of squabbling gods or separate divine beings. This is polytheism, and Christians reject it.

11. Isn’t the Islamic doctrine of the strict oneness of Allah intrinsically better than the Christian doctrine of the Trinity?

This is the belief of Muslims, but they must provide down-to-earth evidence of the superiority of their belief, beyond quoting the Quran or asserting, "Muhammad said so!"

Discussing abstract theology is inadequate. If Muslim theologians discuss the divine attribute of omniscience, then so do Christian theologians. If they discuss the divine attribute of light, then so do Christians. If they discuss the divine attribute of mercy, then so do Christians—and so on. These abstract discussions are endless. So how do we break the deadlock?

How can Muslim theologians provide empirical evidence for the alleged superiority of the strict unity of Allah outside of a supposed revelation in the Quran or outside of an abstract discussion in a theology book? Could they compare the reliability of the Quran with that of the New Testament? But that would take us down a textual path, and still more complications would emerge.

Muhammad would like his followers to believe that military victory is proof of the truthfulness of non-empirical doctrines. After the surprising victory at the Battle of Badr in AD 624, which pitted over 300 Muslim jihadists against around a 1,000 Meccans, he writes in Sura 8, which deals with this battle, the following dubious claim:

8:7 ... [B]ut it was God’s will to establish the truth according to His Word [the Quran] and to finish off the disbelievers— 8 to prove the Truth to be true, and the false to be false, much as the guilty might dislike it. (Haleem)

Muhammad is saying here that Allah’s will was to kill the Meccans, so that Muhammad’s truth would be established. But linking military victory with truth is tenuous. Truth should win out through persuasion, not the sword.

Other than military expansion, how can Muslims prove that their doctrine of strict Oneness is intrinsically better than the doctrine of the Trinity? Somehow God must communicate with humans. Muhammad claims that Allah through Gabriel channeled his messages through him not only for the Muslim community in Medina, but also for the entire world. Allah guided his prophet on a straight path, in his daily life. Here we have a means to test Allah’s revelations to a human: Muhammad’s life.

Unfortunately, for Muslim apologists (defenders of Islam), this test works against them, for Muhammad did not live an exemplary life. In the ten years that he lived in Medina (622-632), he either sent out or went out on seventy-four raids, expeditions or full-scale wars. They range from small assassination hit squads to raids on Meccan caravans, to a military Crusade of thirty-thousand jihadists to Tabuk in the north. So if he did not lead a model life down here on earth, then why should we believe him about abstract doctrines like the nature of God? As noted in this article, he fails Jesus’ simple and down-to earth fruit inspection (Matt. 7:17-20). So we have the right to ignore him in high-minded ideas, for by the fruit of prophets we shall know them. He does not know what he is talking about.

On the other hand, Jesus indeed lived an exemplary and sinless life, so we should to listen to him when he speaks of non-empirical ideas like the Trinity in Matthew 28:18-20. The true God said that he loves his Son and sent down the Holy Spirit to empower him (Matthew 3:16-17), in a majestic and visible affirmation of the Trinity. Jesus walked in perfect and sinless love for humanity. Therefore, we should listen to him in high theology, for he does know what he is talking about.

12. Is the doctrine of the Trinity really that important?

For Christians, the doctrine is indispensable for many reasons, but we focus on two. The doctrine of the Trinity cannot be given up without irreparable damage to Christ’s atonement, first, and salvation or how we get into heaven, second, which is life’s ultimate question.

First, the doctrine of the atonement is jeopardized. This doctrine says that Christ died on the cross for our sins and propitiated divine wrath that was directed at us because our sins. The inspired Apostle Paul says in Romans 8:18-21 that creation itself waits for ultimate redemption. If Christ were a mere creature like us and part of this creation as we are, then he could not have redeemed all of creation. A creature cannot redeem all of creation, of which he is a part. He himself would need redemption. Hence, the eternal Son of God must not be a created being.

Second, justification by grace through faith in Christ is jeopardized, and our salvation goes down the drain. If Christ is not fully God, then how can we trust him to save us in his redemptive act on the cross? We may as well do all kinds of good work, hoping against hope that we may get invited into heaven when we die, but not knowing for sure that God will let us in. Rather, since Jesus Christ was fully divine in human flesh, his salvation is divinely secure for us.

We Christians trust in the Son of God’s good work on the cross and receive his sanctifying Holy Spirit; therefore, our place in heaven is secure. We do not mix up the sequence, doing good works first, and then hoping that we might get into heaven. No, Christ comes first and our trust in him comes second, so now heaven has been promised to us. Only after this sequence do we perform good works, but not to re-earn our place in heaven; rather we do good works out of gratitude to him, in obedience to the Holy Spirit, and out of God’s call on our life. This passage from the Epistle to the Ephesians is one of the clearest on responding to him with good works, after he has saved us:

2:8 For it is by grace you have been saved, through faith—and this not from yourselves, it is the gift of God— 9 not by works, so that no one can boast. 10 For we are God's workmanship, created in Christ Jesus to do good works, which God prepared in advance for us to do.

We have been saved by grace through faith, and even this faith is a gift of God so that we do not boast in ourselves. After we are saved, we do good works, which God has prepared in advance for us to do.

Without the full deity of Jesus Christ, God the Son, our salvation or guarantee to get into heaven becomes shaky. Therefore, the doctrine of the Trinity is a matter of eternallife and death.

We Christians must hold on to the Trinity, as we experience the Father, the Son, and the Holy Spirit in our daily life and in our creeds.

Copyright (c) by James Malcolm Arlandson and used by permission. Originally published at Answering Islam.

Other articles by James Arlandson

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