Imam ar-Razi [1] said in his book  ’Matlib ul-Aliya’ in the chapter on Nubuwah (the prophethood) in the fourth section:

           The effect of the original teaching of Jesus was very limited because he never preached the faith which the Christians ascribe to him. The idea of Father and son and the concept of trinity are the worst kind of atheism and association and are certainly the product of ignorance. Such heretical teachings cannot be ascribed to so great a Prophet as Jesus who was innocent of all such crimes. We are therefore certain that Jesus could have not preached this impure faith. He originally preached monotheism and not tritheism as the Christians claim. But this teaching of Jesus did not spread due to many historical factors. His message therefore remained very limited.

 

[1] Imam ar-Razi, a great authority on almost all the Islamic Sciences and author of many valuable books on Qur’an, hadith history and other sciences.