The Trinity of God is fundamentally a doctrine to the Christian faith. Belief or disbelief in the Trinity would mark orthodoxy from unorthodoxy. Us as humans, can’t fathom the Trinity, nor can logic explain it, and even though the word is not found in the Scriptures, the doctrine is taught.
The term Trinity emphasizes on the three persons but not the unity within the Trinity. The German word Dreienigkeit (“three-oneness”) express the concept further. The definition of the Trinity must include the distinctness and equality of the three persons within the Trinity as well as the unity within the Trinity. The Triunity may better express it. The Trinity is composed of three united persons without separate existence-so completely united as to form one God. The divine nature subsists in three distinctions- Father, Son, and Holy Spirit.
God is one in regard to essence. The essential oneness is shown in Deuteronomy 6:4, “Hear, O Israel! The Lord is our God, The Lord is one! It all means that all three Persons possess the summation of the divine attributes but yet the essence of God is undivided.
God is three with respect to Person. It emphasizes not only the manifestation but also and individual personality. Each has the same essence as God, and each possess the fullness of God. In God there are no three individuals alongside of, and separate from, one another, but only personal self-distinctions within the Divine essence.
The three Persons have distinct relationships. The Father is not begotten nor does He proceed from any person; the Son is eternally begotten from the Father (John 1:18; 3:16, 18; 1 John 4:9). The Holy Spirit eternally proceeds from the Father and the Son (John 14:26; 16:7).
The three Persons are equal in authority. The Father is recognized as authoritative and supreme (1 Cor. 8:6); the Son is also recognized as equal to the Father in every aspect (John 5:21-23); the Spirit is likewise recognized as equal to the Father and the Son.