Muslim vs. Messianic

While reading a recent news article, I thought about how Messianics present themselves as still being part of Judaism despite the fact that Messianic "Judaism" is a branch of Christianity, created by Christianity.

So, let's compare their statements to an item in the news. Sean Stone, famous producer Oliver Stone's son, converted to Islam. He stated to the Agence France Presse: "The conversion to Islam is not abandoning Christianity or Judaism, which I was born with. It means I have accepted Mohammad and other prophets."

Now, does anyone think that he has NOT abandoned Christianity or Judaism now that he has embraced Islam? Of course he has abandoned them for Islam. By that same rationale, Messianics who were born Jewish abandoned Judaism once they embraced the Christian beliefs of Messianic "Judaism."