The answer seems obvious - Jesus Christ. Yet for the Talmudic scholar Hyam Maccoby, this answer is wrong. In The Mythmaker--a work of revolutionary import to New Testament scholarship--Maccoby contends that Jesus was no more the founder of Christianity than the historical Hamlet was the author of Hamlet. Rather, Christianity was the invention of St. Paul, who used elements of Judaism, Gnosticism, and pagan mystery cults as his materials, fusing them around the story of Jesus' crucifixion.

Throughout The Mythmaker, Maccoby wages warfare on time-honored beliefs about the origins of Christianity. He holds that Jesus--in the Gospels a fierce opponent of the Pharisees--was himself a Pharisee; that the self-proclaimed Pharisee Paul never was one; that Jesus' disciples never had any thought of founding a new church; that they never embraced such ideas as Jesus' divinity and the Eucharist, which were brainchildren of Paul; and that the heretical Ebionite sect was really a continuation of the "Jewish Christianity" against which Paul had rebelled.

In progressing from failed rabbinical student to self-appointed apostle, Maccoby's Paul displays the wiliness and, often, the unscrupulousness of a picaresque hero. Yet Maccoby grants Paul a rich, indeed mythmaking, reliogious imagination.

As exciting in its revelations as it is exacting in its methods, The Mythmaker is essential reading for anyone interested in the problematic historical origins of Christianity.

I would agree that Jesus was not the founder of Christianity.

Es_Selam'un Aleykum ve Rahmetullahi ve Berakatuh,

 The name of the Christianity had been found  400 years later from the mission of Hz.Jesus(a.s.);it is valid from the scientific researches,from the history and from the holy book Qur'an;Hz.Jesus(a.s.) was using Islam for the name of His religion,mission....

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YUSUFALI: When Jesus found Unbelief on their part He said: "Who will be My helpers to (the work of) Allah?" Said the disciples: "We are Allah's helpers: We believe in Allah, and do thou bear witness that we are Muslims.

Angel wrote: Some one brought this up in another thread, somewhere, is Christ actually Jesus's last name or is it that some one gave it later. If Christ is the last name, then I would understand how Christianity come about

His name according to Holy Qur'an was 'Essa son of Mary' - no other family name.

How it became Jesus or Christ can be found from this article.

http://answering-islam.org.uk/Green/barnabas.htm - http://answering-islam.org.uk/Green/barnabas.htm