What is left of Judaism today is a corrupt religion, from a true Christian perspective. They do not worship the one true God which means that their minds are darkened. Those Jews who where chosen of the Father and Son became the foundation of Christianity and everything that encompasses, including the theology of Satan. The things we believe about Christ, the resurrection, Satan and everything else has been handed down to us from our Jewish founders.
Gentiles are grafted into the belief structure established by our Jewish founders. You seem to be saying Judaism and Christianity were two seperate religious beliefs. This is not the case.
There was no such thing as the Judaism. Christianity was only one version of it. However, all forms of Judaism have certain things in common.
But when +Paul broke with the Law and circumcision, Christianity ceased being a form of Judaism.