While the doctrine of the Trinity has been most widely accepted by orthodox Christians since the early days of the church there are still some holdouts to this blessed, biblical, and orthodox doctrine of God.
Below is a question and answer with scriptural support from the Westminster Larger Catechism dealing with the Trinity.
Q. 11. How doth it appear that the Son and the Holy Ghost are God equal with the Father?
A. The scriptures manifest that the Son and the Holy Ghost are God equal with the Father, ascribing unto them such names (Isa 6:3, 5, 8; with John 12:41; with Acts 28:25; Jer 23:6†; 1 John 5:20; Ps 45:6†; Acts 5:3-4), attributes (John 1:1; Isa 9:6; John 2:24-25; 1 Cor 2:10-11; Heb 9:14†), works (Col 1:16; Gen 1:2; Job 26:13†; John 1:3†), and worship (Matt 28:19; 2 Cor 13:14), as are proper to God only.