What is the Trinity?
The word "Trinity" does not appear in Scripture itself, but it expresses one of the most foundational truths of the Christian faith: that there is one God who exists eternally as three distinct Persons — Father, Son, and Holy Spirit — equal in nature, united in will and purpose, yet personally distinct.
Morrish's Bible Dictionary gives a concise definition:
Morrish's Bible DictionaryA word only used to convey the thought of a plurality of Persons in the Godhead. This was revealed at the baptism of the Lord Jesus. The Holy Spirit descended 'like a dove' and abode upon Him; and God the Father declared "This is my beloved Son in whom I am well pleased." That the Father is a distinct Person and is God is plainly stated, as in John 20:17. Many passages prove that the Lord Jesus is God: one will suffice: ". . . . in his Son Jesus Christ. This is the true God, and eternal life." 1 John 5:20. That the Holy Spirit is a Person and is God the following passages clearly prove: Gen. 1:2; Matt. 4:1; John 16:13; Acts 10:19; Acts 13:2, 4; Acts 20:28; Rom. 15:30; 1 Cor. 2:10. The three Persons are also named in the formula instituted by Christ in baptism. Matt. 28:19. Yet there is but one God. 1 Tim. 2:5.
One of the most striking evidences for the Trinity appears on the first page of the Bible. A.J. Pollock draws attention to the Hebrew word *Elohim*:
A.J. PollockMoses left to himself would never have written the name of God in the plural. In the Hebrew language there are three numbers, *singular*, one, and one only; *dual*, two, and two only; *plural*, three at least, or more. The idea of the Trinity is undoubtedly enshrined in the word, God, being in the plural. That being so we have God, the Father; God, the Son; and God, the Holy Spirit.
He further explains how the grammar of Genesis 1:1 expresses both plurality and unity at once:
Moreover in Genesis 1:1, the verb, *created*, following the plural noun, is in the singular, showing that there is only one God, though there are three persons in the Godhead, a plural unity, if we may so phrase it.
And regarding Deuteronomy 6:4 — "Hear, O Israel; the LORD our God is one LORD":
This clearly shows that whilst Scripture affirms that there are three distinct Persons in the Godhead, yet there are not three Gods, but one; not a trinity of Gods, but a triune God.
A.J. Pollock also notes that the name *Adonai* is, like *Elohim*, in the plural:
A.J. PollockThese Three Persons, of one Substance, completely united in thought, will, purpose, counsel, are not three Gods, but One God, not a tritheism, but a Holy Trinity. We cannot understand the mystery of all this, but this truth lies at the very foundation of the Christian faith.
Pollock highlights a striking passage from Isaiah 48:16 where a Divine Person speaks:
"Come ye near unto Me, hear ye this; I have not spoken in secret from the beginning; from the time that it was there am I: and now the Lord GOD, and His Spirit, has sent Me."
Who is this that can speak of Himself as existing before the beginning? Surely none but a Divine Person. Here we have the Trinity — "The Lord God and His Spirit has sent Me" — "Me," the Word of John 1:1, and one of the persons of the Elohim of Genesis 1:1, the Lord Jesus Christ.
William Kelly takes care to show that while the three Persons are one God, they must not be confused with each other. Commenting on 2 Corinthians 3:17 ("Now the Lord is that Spirit"), he writes:
William KellyIt is impossible to print "spirit" in that verse with a capital "S" consistently with truth. For this would identify the second person of the Trinity with the third, which is wholly untrue.
But the moment you come to the next clause, "Where the Spirit of the Lord is," you must have a capital "S," because the Holy Ghost is meant. The Lord has gone on high, but the Holy Ghost is sent down below; and He it is who now seals the believer, bringing him into liberty in Christ.
V.W.J.H. Lockyer traces the conflict back to the Arian heresy, when the essential relationship of Father and Son within the Godhead was attacked:
V.W.J.H. LockyerThe truth that God had verily sent His Son into the world was to them, as to all, heretic and orthodox alike, the only possible meaning of the words of Scripture. The question at issue was, In what sense was this glorious Person the Son of God; was it only in a created sense, supremely great and wonderful, or was it in an essential Sonship, a relation in which He was both substantially and eternally one with the Father?
The Trinity is the foundational truth that there is one God who has eternally existed as three distinct Persons — Father, Son, and Holy Spirit. This is not a later theological invention but is woven into the very fabric of Scripture from its opening verse, where the plural name *Elohim* is paired with a singular verb — signalling both plurality of Persons and unity of being. Each Person is fully and equally God: the Father is God, the Son is God, the Holy Spirit is God — yet there are not three Gods but one. The Persons are distinct — the Father is not the Son, the Son is not the Spirit — yet they are of one substance, perfectly united in thought, will, purpose, and counsel.