Christ was a Jew, and practiced the Jewish religion. Why would He establish another religion when the religion of God was already in existence?

As stated above, God gave the true religion to mankind gradually, so that men would be prepared by more simple doctrines for still more noble truths. Thus He sent Moses the lawgiver, and after him a series of prophets to explain the law and to predict the coming of the Messiah. Christ fulfilled these predictions and taught the perfect law of God. The religion known by the Jews before Christ was therefore but imperfect and preparatory. The religion of Christ was its perfect fulfillment, and the Jews should have recognized and accepted it. They did not, and then Christ sent his Apostles to preach it to the Gentiles. Christ did not therefore establish another religion. Christianity is the perfect development of the Jewish religion, just as the perfect tree is the perfect development of the seed from which it grew.

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty