Historical facts reveal that Jesus did not use the word Christianity. He and his followers used to worship in the temple which other Israelites used. The message of Jesus was to call people back to the religion of Abraham and Moses from which they had gone astray. After the disappearance of Jesus, Paul declared that belief in Jesus sufficed for salvation. The Jewish scholars of that time called the followers of prophet Jesus the misguided sect of Nazarene or Galilaens. In 43 C.E., when Paul and Barnabas went to Antioch to preach, they were ridiculed and were called Christians by the masses. The ones who were called Christians felt that if they are being given a name in reference to Jesus, there is nothing wrong in accepting it. A present day analogy may be the case of Muslims being called Mohammedans in the West and Muslims giving in to the name.
PAUL ALTERED THE MESSAGE
1. the concept of Jesus as son of God;
2. Jesus died on the cross to wash eternal sins of Adam's children through his blood; and
3. the Law of Torah was renounced. He eliminated all regulations concerning food and abrogated the injunctions of circumcision.
The real followers of Jesus opposed these blatant misrepresentations of the message of Jesus. Their struggle to reject the notion of Divinity of Jesus continued for about two hundred years. Since these alterations were very appealing to the Gentiles, the true believers were unable to stop the misguidance.
In 325 C.E., a council of Christian leaders met at Nicaea and officiated Paul's beliefs as their religion. Roman Empire declared Paul's religion as the religion of the State and all those books which denied these beliefs were banned. In 367 C.E., the State announced a list of books acceptable to it and fifteen years later, a council held under the presidency of Pope Damasius gave its approval to these books. At the end of the fifth century, Pope Galasius published a list of unauthorized books (Apocryphal) to further conform with Paul's religion of Christianity.
Source:University of Northumbria at Newcastle. Islamic Society.