Simply stated: “The Trinity is three persons (personae) in one substance (substantia).”

“We worship one God in Trinity, and Trinity in Unity; neither confounding the persons, nor dividing the substance.” — The Athanasian Creed

“Within the One Being that is God, there exists eternally three coequal and coeternal persons, namely, the Father, the Son, and the Holy Spirit” (James White, The Forgotten Trinity, p. 26). 

What Are The Foundations For The Trinity

In one sense the doctrine of the Trinity is a mystery that with our finite mind will never be able to understand fully. However, we can understand something of its truth by summarizing the teaching of Scripture.

From the above definitions we can observe three points:

First, the doctrine rests completely upon the truth of the first clause: there is only one God (Deuteronomy 6:4-6; Isaiah 43:10). Second, the definition insists that there are three divine persons (Matthew 28:19; 2 Corinthians 13:14; Jude 20-21).[1] Third, we are told that the relationship among these divine persons is eternal. God the Father is clearly God (John 17:5; Romans 16:26). The Son is fully God (Isaiah 9:6; Matthew 16:16; John 10:36; 17:5). The Holy Spirit is fully God (John 16:7-8; 1 Corinthians 3:16; Hebrews 9:14). They have eternally existed in this unique relationship. The Father is not 1/3 of God, the Son 1/3 of God the Spirit 1/3 of God. Each is fully God, coequal with the others, and that eternally.

Foundation One: Monotheism: There Is Only One God
Foundation Two: There Are Three Divine Persons
Foundation Three: The Persons Are Coequal and   Coeternal

These three foundations not only provide the grounds upon which the Trinity is based, they explain to us why Christians who accept all of the Bible believe this doctrine.

Often we are asked: “How can you claim to only believe the Bible, when you use terms like ‘Trinity’ that don’t appear in the Bible?” we must be quick to point out that we are forced to do so by the teaching of the Bible itself on these three points. Every error and heresy on this doctrine will find its origin in a denial of one or more of these truths.

What Kind of Unity is God?

Christians believe in the unity of God: that God is only one. By the unity of God we mean that there is but one essence (the totality of God’s infinite perfections) in the Godhead, and this one essence wholly, equally, and eternally pervades (is diffused throughout) each of the three persons of the Godhead without division or multiplication. Each person subsists [exists, lives] in the essence. God is three persons in one and the same essence. The unity of God indicates that He is not divided or divisible [separable] in His essence; His essence is “simple” (Rolland D. McCune, Systematic Theology I, Detroit Baptist Theological Seminary, pp. 165-166).

The essence is not divided among the persons of the Godhead. It can wholly and indivisibly be in more than one person. The doctrine of the Simplicity of God means that He is incapable of division because He is the perfect Spirit. A Trinitarian person is not a fractional part of the essence (ibid).

The essence exists only as in the persons of the Trinity; it exists only as trinalized. The one essence is simultaneously [at the same time] three persons, and is eternally so. God did not exist singly in essence only for a time, and then became trinal. Nor will He cease to be three persons (ibid).

A unit is marked by singleness incapable of internal distinctions. If we believe that God is a unit then the question left is: What was God doing before creation? Did He speak? Did He love? The belief in a Triune God is the only explanation to this philosophical question. God in His tri-unity was expressing these things to each of the Persons of the Godhead. The Trinitarian view of God sees the Persons of the divine Trinity as being active before time. God is a unity not a unit. God is a unity of one essence in three distinct persons. Both the Old and New Testament stressed this unity of God and never actually delineates His tri-unity (Deuteronomy 6:4-5; cf. 4:32-35, 39 God is the only one [“there is no other”] quantitatively; 32:39; James 2:19; 1 Corinthians 8:5-6).

Did Christ Say I am God? 

Many of our Muslim brothers claim that Jesus never in the Bible declared that he is God. The Bible reveals that Jesus was self-conscious of His Deity.

  • HIS AFFIRMATION TO BE YAHWEH (JEHOVAH)—Yahweh or Jehovah is the special name given by God for Himself in the Old Testament (Exodus 3:14, 15). When God said, “I AM WHO I AM” He was saying that I am self-existent. Christ said in John 8:58 “Before Abraham was born, I am!” This statement claims not only existence before Abraham, but equality with “I AM” of Exodus 3:14.

He Forgive Sins—only God can forgive people their sins, since all sins are ultimately against Him who is sovereign over the universe. Jesus exercised the divine authority of forgiveness (Mark 2:5; Luke 5:20-25).

His Giving Life (John 1:3-4; 5:21, 25; 6:32-34; 11:25-26)

His Exercising Judgment on the World (Matthew 25:31-46)

His Expressing Divine Authority—only one who is God could exercise such authority as that seen in Jesus’ rebuking His enemies, like Satan (Matthew 4:10; 16:23; cp. Jude 8-9) and demons (Mark 1:24-26), and in His declaring additional or new moral laws (Matthew 5:28, 32, 34, 39, 44).


Jesus made assertions that would have been blasphemous if they were untrue. On the other hand, only One who was God could have said these things without lying.

He Affirmed His Equality to the Father—He asserted His equality to God the Father in receiving honor (John 5:23), in being the object of faith (John 14:1; 12:44), in His words and works (John 5:19; 12:49-50; 14:10, 24), and in His revelations (John 12:45; 14:19).

He Affirmed His Unique Relation to the Father (John 14:7-10, 20).

He Affirmed His Ability to Satisfy People’s Deepest Needs (John 4:14; 6:35; 7:37-38; 10:9-10; Matthew 11:28-30)

He Affirmed His Ability to Give Eternal Life and Safety to His People (John 6:37-40; 10:27-29).

HIS RECEIVING HONORS DUE ONLY TO GOD (Matthew 8:2; 28:9, 17; John 5:23; 20:28).

My friend, the Christian belief in a Triune God is not blasphemy to God but making justice to the uniqueness of God. Again we do not believe in three gods as the Muslims believe but we believe in One God in three Persons, these three Persons being fully God.

I invite you to accept Christ as your sovereign Lord and Savior. Acknowledge that you are utterly sinful and wicked (Romans 3:10-12), by no means seeking after God, but died in sins and transgressions (Ephesians 2:1-3). Yet God being abundant in grace and mercy demonstrated His love toward sinners like us and made us alive. Thus, you have to repent and believe (Acts 20:21) in the most Glorious and Holy God and in His Son Jesus Christ who died on the cross to provide the satisfactory sacrifice for our sins (2 Corinthians 5:18-21) that would please the most righteous and holy demands of God (John 1:29; Galatians 1:3-5; Hebrews 9:11-14; 1 John 2:1-2). For the inspired Word of God declares that “the wages of sin is death…” (Romans 6:23). Therefore, come to God crying out for mercy and forgiveness. For “in the past God overlooked such ignorance, but now he commands all people everywhere to repent. For He has set a day when he will judge the world with justice by the man He has appointed [the Lord Jesus]. He has given proof of this to all men by raising him from the dead” (Acts 17:30-31).

[1]What “person” means when we speak of the Trinity is quite different than when we speak of creatures such as ourselves. These divine persons are identified in the last clause as the Father, the Son, and the Holy Spirit.