It’s Christian in the same way Christianity is Jewish.
Indeed, Jews may contradict Christianity, but biblical Judaism does not, it cannot! All of scripture is the inspired word of God.
It is possible to be a Christian based only on the teachings of the old testament — everything Christianity teaches is found within the old testament: “The new within the old concealed. The old within the new revealed.” Throughout the new testament, constant reference is made to the old, and points out where Christ fulfills the law, fulfills prophecy, nothing taught by Christ contradicts the Holy Scriptures of the Jews.
Mormonism, on the other hand, utterly contradicts biblical Judaism and Christianity.