Which key theological principle is a fundamental difference between judaism and christianity?

Old testament is associated with Judaism and the new testament is with Christianity

One of the key theological differences between Christianity and Judaism has to do with Jesus. While Christians believe that Jesus was/is the Messiah (the savior of people), Jews generally believe that Jesus was not the Messiah and that the Messiah has not come yet.The Jews rejected Christ's claim that he was the Son of God. They believed His claim was blasphemous the Jews reject the New Testament and read only Hebrew Bible which is called theTanach. The first five books of the Hebrew Bible contain God's guidelines for  how Jews are meant to live. Paul wrote (Galatians 3v10) that anyone who wants to live under the law is under a curse. According to the N.T. we are released from the curse of the law by faith in Christ. One answer by a Jew Judaism was already a complex and complete religion for thousands of years before Christianity even began evolving. Christianity represents, if anything, the rejection of Judaism - as it contradicts some core Jewish tenets. Now, this is not to imply that one faith is better than the other: it is merely to clarify how profoundly different these two religions are. It is, of course, true that Christianity began life as a tiny fringe sect within Judaism. But the original followers of Jesus were not called 'Christians'. They called themselves followers of Jesus were not called 'Christians'. They called themselves followers of "The Way", "ebionim/ThePoor" and "Notzrim/HolySeparatedOnes"Most of the Christian doctrines did not develop until Saint Paul (after Jesus'death) and much later with the Church fathers and Constantine, by which time Christianity was already an entirely non Jewish faith. The final and irrevocable parting of the ways between the faiths came when Christians deified Jesus (formalized by Constantine in 325CE). At this point, Christianity was endorsing a belief that is blasphemy for any Jew, because in Judaism, no human can ever be 'divine' or on a par with G-d. Judaism was already a complex and complete religion for approximately 1500 years before Christianity even began evolving see discussion page. Christianity contradicts core Jewish tenets.Here are just some of the differences in key beliefs between Judaism and Christianity: 1. Judaism: - says that no human can ever die or atone for the sins of others and sins can only be atoned for by animal sacrifice or prayer and restitution Christianity: - says that Jesus died for the sins of mankind 2. Judaism: - says that all humans are born pure, and innocent Christianity: - says that all humans are born with 'original sin'. 3. Judaism: - says that no man gets a 'second coming' and the Messiah will not need one Christianity: -human should speak directly to G-d (without intermediaries) Christianity human should speak directly to G-d (without intermediaries) Christianity*5 Judaism: - says G-d is one, indivisible, cannot be separated into three aspects/incarnations Christianity: - speaks of the Father, the Son, and the Holy Spirit 6. Judaism: - says that we are all equally G-d's children 

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