Question: Can Christianity be construed as a form of Judaism?
Answer: The early followers of Jesus were Jews and they believed that they were following Judaism in their belief in Jesus as their expected Messiah. As the message of Jesus spread to gentiles, a result of the missionary work of Paul, the movement became made up of Jews pulling towards original Judaism and the gentiles pulling away from it. This confusion continued until the Council of Nicea in 325 C.E. convened by Constantine. The Council decided to make a clean break with Judaism, for example, moving the Sabbath from the traditional Saturday observance to Sunday. Most important, was the decision to consider Jesus to be a part of Gd rather than a mortal man. This belief was antithetical to Judaism which forbids a corporeal image of Gd.
So, although early Christianity was an offshoot of Judaism, modern Christianity is a contradiction to Judaism.
Rabbi Azriel Schreiber