Full Idea
Jesus himself certainly never claimed to be God, and the doctrine that Jesus had been God in human form was not finalised until the fourth century.
Gist of Idea
The idea that Jesus was God was only settled in the fourth century
Source
Karen Armstrong (A History of God [1993], Ch.3)
Book Reference
Armstrong,Karen: 'A History of God' [Mandarin 1993], p.98
A Reaction
It was this final view which seems to have provoked Muhammed into developing a religion with the slogan "there is only one God". In Christianity an initially promising set of teachings grew into a prolonged irrational hysteria.