The doctrine of the Trinity is something we often shy away from as Christians. It is something we find hard to understand let alone communicate. We often have a perception that it is a topic for advanced Christians or theological students, and when it comes to evangelism, many of us have had complicated and difficult experiences talking to people from a Jehovah Witness or Muslim background and therefore as much as possible avoid speaking about it.
However, the doctrine of the Trinity is a foundational doctrine for Christians, and rather than an advanced topic that should be left to be taught in Bible schools, it is a key, foundational description of who our God is, and not only an important topic for Christians to grasp, but it can also be useful in evangelism too.
Christians and others often claim that the Trinity is difficult to explain or define. However, while as we’ll see, there is mystery in the Trinity, defining it is quite straight forward. Grudem, a Christian scholar defines the Trinity as follows: “God eternally exists as three persons, Father, Son, and Holy Spirit, and each person is fully God, and there is one God.”1 The Christian teaching of the Trinity is a response to these three truths taught clearly in the Bible.
The fact that there is one God is not something Muslims and Christians disagree over. Monotheism is the belief in and worship of only one God. Both Muslims and Christians are monotheists. Muslims however, claim not just to be monotheists, but “pure monotheists”2, believing in "Tawhid," the fundamental belief that there is only one God, Allah, who is unique, indivisible, and without any partners. Quran 112.1-4 states that “He is Allah, [who is] One, Allah, the Eternal Refuge. He neither begets nor is born, nor is there to Him any equivalent”.
The Bible too is clear that there is one God. Deuteronomy 6:4 clearly shows that God is one, “Hear, O Israel: The Lord our God, the Lord is one.” In Isaiah God says, “Before me no god was formed, nor will there be one after me. I, even I, am the Lord, and apart from me there is no saviour”. (Isaiah 43:10-11) and ““This is what the Lord says- Israel’s King and Redeemer, the Lord Almighty: I am the first and I am the last; apart from me there is no God.” (Isaiah 44:6).
Jesus too in the New Testament affirms this belief, saying ““Hear, O Israel: the Lord our God, the Lord is one” (Mark 12:29) and “this is eternal life, that they know you, the only true God, and Jesus Christ whom you have sent.” (John 17:3). The writers of the epistles also affirm the fact there is one God, “For there is one God and one mediator between God and mankind, the man Christ Jesus” (Paul in 1 Timothy 2:5) and “You believe that there is one God. Good! Even the demons believe that – and shudder.” (James 2:19).
Where Christians and Muslims disagree, is in their understanding of God’s oneness. The Quran teaches that God is an indivisible unity, whereas the Bible says God exists as one God eternally existing in a plurality of persons.
The Bible presents us with many characters and figures who almost exclusively possess attributes of created creatures whether human or angelic. Adam is created by God from the dust of the ground. Angels are also created by God (see Nehemiah 9:6 and Colossians 1:16). The exception is God himself who as God, naturally possesses all the qualities and attributes of God, uncreated and eternal, all powerful, all knowing etc. However, as we read Scripture, we are introduced to three individuals or characters who not only possess attributes that only God can possess but also are worshipped and honoured in a way that only God should be honoured.
So, while the Bible is full of references to God as the one God (whom Christians would say include all three persons of the Trinity), for example Deuteronomy 6:5, we see the Father as God. In John 6:27 for example, Jesus calls God “Father”, as he does in the Lord’s prayer. As we are introduced to Jesus, while in his incarnation some of his eternal qualities are hidden, he is clearly described as God. In John 1:1-3 we are told he is God, and that all things were created by him. He too claims to be God himself in John 8:583 by using the personal name of God for himself and claiming to be eternal, something that those listening to him clearly saw as a blasphemous claim to deity4.
The Quran however categorically rejects the idea that Jesus is God or that God exist in three persons. Quran 6.101 says, “[He is] Originator of the heavens and the earth. How could He have a son when He does not have a companion and He created all things? And He is, of all things, Knowing.” And Quran 72.3 says “And [it teaches] that exalted is the nobleness of our Lord; He has not taken a wife or a son”5.
We are also introduced to the Spirit, who is also said to be God. While the Quran makes reference to the Spirit (in Arabic Rūḥ al-qudus - see for example Quran 2.87, Quran 2.253, Quran 5.1106), Muslims claim these are references to the angel Gabriel7, and while we welcome the recognition that the Spirit is a person8, not an inert force as the Jehovah Witnesses claim9, the Bible clearly teaches that the Spirit is God himself. Key references for this are Acts 5:3-4, where Peter equates lying to the Spirit as lying to God and 2 Corinthians 3:17 which explicitly claims that “the Lord is the Spirit”.
One heresy that the early church contended with was the heresy of Modalism or Sabellianism10 which teaches that there is essentially only one person or “hypostasis” in the being of God. Modalism11 teaches that God reveals himself in different modes or roles like a single actor playing multiple characters in a movie.
However, in the Bible we see each person operating independently from and in relationship with each other. Jesus prays to the Father (see for example his high priestly prayer in John 17). John 1:1 also shows us that the Word (Jesus) was with the Father. John 5:23, John 8:16 and many other verses in John show us that the Father sent Jesus into the world, and in John 14:16 the Father (in John 16:7 Jesus) sends the Spirit. In Mark 1: 9-11 we see the three persons of the Trinity working together yet independently from each other as Jesus is baptised, while the Father speaks from heaven and the Spirit descends on Jesus12.
Muslims sometimes ask, “why three?” or “why stop at three?”13 The answer is, we are constrained by the witness of Scripture that only presents three, the Father, Son and Spirit as divine, and therefore the Trinity is the “best explanation of the data at hand14.”
Probably the hardest part of the Trinity to understand is the idea that each person in the Trinity is fully God. When we say that each person is fully God, we mean that each person owns each attribute of God, but also therefore that in himself each person carries the full essence of the being of God. Each attribute, omnipotence (all-powerful), omniscience (all-knowing), omnipresence (present everywhere), eternality (existing outside of time), holiness (perfect moral purity), love, justice etc, can only flow out of that one essence or being.
Denying this, results in polytheism, or tritheism, the belief that the three persons of God are separate individual gods.
While, claiming the Father is fully God isn’t controversial, claiming this of Jesus is certainly where we admit that there is mystery in the Trinity. However, this is clearly what the Bible teaches.
Speaking of Jesus, John 1:1 says that he “was God”, not “a separate God” apart from the Father15, Jesus says to his disciples, “If you have seen me, you have seen the Father” (John 14:9), not claim that he was the Father, rather than as the Son he shares the same essence of the Father. Hebrews 1 speaks of Jesus being the “exact representation of [God’s] being” (Hebrews 1:3). Paul to states in Colossians 2:9 that “all the fulness of the deity dwells in” the person of Jesus.
Again, this is where the mystery of the Trinity lies, with Muslims claiming that there is a contradiction at the heart of the Christian understanding of God. Grudem however says, “to say that ‘God is three persons and there is one God’ is not a contradiction. It is something we do not understand, and it is therefore a mystery or a paradox, but that should not trouble us as long as the different aspects of the mystery are clearly taught by Scripture, for as long as we are finite creatures and not omniscient deity, there will always (for all eternity) be things that we do not fully understand.”16
How these three topics fit together is outside of the scope of our experience or ability to define within the bounds of our own logic. This should comfort us, as if the Trinity was completely explainable it would suggest that God was a product of our own thinking. It’s also worth noting that there are many examples from science of things we know are true but don’t know how they fit together. For example, how light is both a wave and a particle or how the rules of classical and quantum physics coexist. If there is mystery in what God created, how much more should there be things about God’s nature that will be beyond us.
The theologian Berkhof explains the nature of the mystery at the heart of the Trinity: “The Trinity is a mystery…man cannot comprehend it and make it intelligible. It is intelligible in some of its relations and modes of manifestation, but unintelligible in its essential nature…. The real difficulty lies in the relation in which the persons in the Godhead stand to the divine essence and to one another; and this is a difficulty which the Church cannot remove, but only try to reduce to its proper proportion by a proper definition of terms. It has never tried to explain the mystery of the Trinity but only sought to formulate the doctrine of the Trinity in such a manner that the errors which endangered it were warded off.”17
As we seek to explain the Trinity to others, holding to these three key truths will keep us from heresy. In seeking to explain the Trinity, Christians often use illustrations or objects from everyday life to explain the Trinity in a way that people understand. We need to be careful however, as nothing created can ever explain God’s nature fully. If such thing existed, it would need to be grater or equal to God. See “One can sometimes equal three!” for more on this.
The Quran on the other hand denies the Trinity. Quran 4.171 says, “O People of the Scripture, do not commit excess in your religion or say about Allah except the truth. The Messiah, Jesus, the son of Mary, was but a messenger of Allah and His word which He directed to Mary and a soul [created at a command] from Him. So believe in Allah and His messengers. And do not say, "Three"; desist - it is better for you. Indeed, Allah is but one God. Exalted is He above having a son. To Him belongs whatever is in the heavens and whatever is on the earth. And sufficient is Allah as Disposer of affairs.”
The Quran goes as far as to say that holding to any view where one “associating others to God”, are committing a sin that will not be forgiven, also known as the sin of “Shirk”: “Indeed, Allah does not forgive associating others with Him “in worship”, but forgives anything else of whoever He wills. And whoever associates others with Allah has indeed committed a grave sin.” Quran 4.48
It is clear though that the writer of the Quran misunderstands the Trinity, falling into the heresy of “tritheism”: “And [beware the Day] when Allah will say, "O Jesus, Son of Mary, did you say to the people, 'Take me and my mother as deities besides Allah?'" Quran 5.11618 See “The Misunderstood Trinity in the Quran” for more on how the Quran misunderstands the Trinity.
Referencing the Trinity in evangelism or defending the Christian view, we need to first point out what Christians and Muslims understand by the Trinity. As stated above, stating the three key truths that define the Trinity is not difficult, and we shouldn’t be worried about showing a healthy humility in understanding the nature of God. Pointing out the Quran’s failure to understand the Trinity might also be useful in conversations. (See again, “The Misunderstood Trinity in the Quran”)
We often shy away from mentioning the Trinity in discussions, however, it can be a helpful in showing the beautiful nature of God.
In discussions, there is value in focusing on dynamics of the relationship that have always existed in the Trinity for eternity. The Bible says that God is love, and he has always been love. Love however requires relationship. The Quran states that God “does not have a companion” (Quran 6.101) How then can he be truly loving without being dependent on creation if “Self-Sufficient” is one of the 99 names of Allah? See, “Only a Trinitarian God can be a God of love”.
Related to this is the fact that the Christian view of salvation is reliant on the God being Trinity.
If Jesus were not fully God, he wouldn’t have the capacity to pay for sin, but the Father in love sends his Son to take on himself the shame and penalty of our sin. The Spirit’s work in us to transform us into the likeness of Jesus is also dependent on who the Spirit is.
The doctrine of the Trinity therefore shapes the Christian understanding of salvation by showing us the roles of each person of the Godhead in initiating, accomplishing, and applying redemption to humanity, and by highlighting the unity and harmony of God's saving work.