There is 1 Faith and that is Judaism / True Faith of Abraham, Isaac and (Jacob/Israel).
We may be misunderstanding each other by using the same word and meaning two different things.
When most of us say "Judaism", we are referring to Talmudic Judaism, the religion that is outlined in the Talmud, which was compiled several centuries after Messiah. It is based on the beliefs of the Pharisees, who did exist in New Testament times - and were, until the coming of Messiah, following something very close to the true faith, with only errors in details. However following the coming of Messiah those who were attempting to follow Abraham's faith divided into those who accepted Messiah, and those who rejected Him.
Those who rejected Him further developed their religion to become Judaism. They compiled the Talmud to outline the tenets of this new religion, and explicitly reject Messiah. They also shortened the Tanach by rejecting those scriptures which were not in alignment with their new religion, which is why the Masoretic Hebrew Tanach (the Protestant Old Testament) contains fewer books than the older Dead Sea Scrolls and LXX.
At the same time, those who accepted Him formed Christianity. They compiled the collection of books of the New Testament to codify this faith. They also preserved the longer, original Tanach - but unfortunately only preserved it in Greek, not Hebrew (forming the Catholic and Orthodox Old Testaments, and the Protestant Apocrypha).
A few hundred years later, a bunch of savage desert dwellers tried to resurrect the ancient simpler faith of Abraham, but under the influence of a demon pretending to be an angel ended up forming Islam, a simpler but far more murderously brutal faith than either of the above...
Neither Judaism, nor Christianity (and certainly not Islam), was the religion of Abraham. Abraham's faith was simpler than any of these, as less had been revealed to him - he lacked the revelations given through Moses and Yeshua.
So what do you mean when you say "Judaism"? Do you mean Talmudic Judaism? Do you mean the simple religion of Abraham (which was different)? Do you mean something else? This may be at the heart of our misunderstandings.