What evidence is there in scripture to support the doctrine of the holy trinity?

I have a close friend that is a very devout Jehovah’s Witness; he and I are currently undertaking a study of the word of God together and the more I learn about the witnesses’ faith the less inclined I am to agree with any of their beliefs.  My friend and I argue over the doctrine of the holy trinity, he calls me a pagan and says that the trinity is never mentioned in the bible.  Other than John 1:1 what other evidence in scripture is there that supports the doctrine of the holy trinity?

Clarify • Share • Report • Asked September 08 2013 • Simon Cropper