In the case of christianity, its not judeo -christian, but firm and strong in greco-roman. They didn't receive jews in abundance. They received the gentiles. And why not get gentiles ? The more the merrier, now the gentiles have something in common with the form of worship they already know, polytheism. The father, the son, and this spirit thing, and at the same time this man is his own father, plus the jews hate this man, so its gotta be something better. And it can be an abrahamic faith. We can compete with them, and show them polytheism can dominate. And it did dominate. Don't worry, paul (who never met jesus) is our guide. He says we can be circumcised or not, it doesn't matter.
ALSO, meat sacraficed to idols is okay, no more kodesh, no more halacha, no more kosher,. Lets bless this food to paganism it doesn't matter because paul says so.