Questions on the Trinity for Muslims - Briefly, what is the Christian doctrine of the Trinity?
God is not subject to man's limitations, and God can reveal Himself to us however He wants. The Trinity actually is not just one doctrine, but seven doctrines that God has revealed in the Bible.
There is a threeness in Scripture: Matthew 28:19 ("...baptizing them in the name of the Father, and of the Son, and of the Holy Spirit"); 1 Peter 1:2; Ephesians 2:18; Revelation 4:8; 2 Corinthians 13:14; John 15:26.
There is only One God. Deuteronomy 4:35-39; 6:4; ("Hear O Israel, the Lord your God is One") Isaiah 43: 10-2; 44:6,8; 45:5-6,14,21; 46:9; 1 Timothy 1:17;6:15-16.
Three distinct persons: Matthew 3:16-17; Luke 3:21-22 (at Jesus baptism the Father spoke and the Holy Spirit descended as a dove); John 1:1;6:38;14:31;15:26; 16:28; 17:5; Acts 5:31-32; Mark 10:38-40. Even simple things on earth, such as fingers on a hand, lobes of a cloverleaf, or peaks in a mountain range can be distinct and not separate. God can have distinct parts and still be inseparable too.
Jesus is God. John 1:3 ("In the beginning was the Word, and the Word was with God, and the Word was God"); John 9:38 ("The man said, 'Lord I believe,' and he worshiped him.") Colossians 1:16-17; Hebrews 1:6-9; John 9:38; 2 Corinthians 11:3; John 20:28-29; Revelation 5:8-9;22:20
The Holy Spirit is God. 1 John 4:12-16 ("... God lives in us and his love is made complete in us. We know that we live in him and he in us, because he has given us of his Spirit.") Romans 8:9-16; Luke 1:35; 1 John 4:12-16; 1 Corinthians 3:16 vs. 1 Corinthians 6:19; Acts 5:4
They are equal in nature, glory, and honor. John 5:18; 5:23 ("...all must honor the Son just as the honor the Father who sent Him"); Colossians 2:9-10; (Isaiah 44:6; Revelation 1:8 vs. Revelation 1:17-18; 22:13)
They differ in role and rank. Philippians 2:5b-6 "Christ Jesus: Who, being in very nature God, did not consider equality with God something to be grasped [held onto] but made himself nothing, taking the very nature of a servant, being made in human likeness." 1 Corinthians 11:3; 1 Corinthians 15:25-28; Matthew 12:18; Ephesians 1:3,17; John 1:33; 14:16,26,28; Romans 8:26-27. A common metaphor is that on earth a father and son are equal in value, the same nature, etc. However, the father has a different role in the family than a son.