fact finder - your statement "A person cannot be a "Jewish" Christian! Both religions are too different and are at odds." is factually incorrect. An example of a Jewish Christian - Peter.
Peter was Jewish by birth, and he continued to practice Judaism after he became a Christian (A Folllower of Christ) A jewish Christian would be someone that is first and foremost a member of the Jewish faith (He continues to observe the Mosaic Law) , and secondly he accepts Jesus as the Messiah (Not as God)
Also I agree that both religions are quite different, however his is not because of Jesus, this is because of Paul. Jesus had the objective of ending Animal Sacrifice and teaching and showing by Example how to properly follow The Law. He did not start Christianity as we kmow it, that was Paul that started A new Religion, with his " Saved because of Faith" and "Ransom Sacrifice" doctrine.
By the way.. I agree that the 144,000 are Jewish Christians.