That is incorrect. Gentiles have been grafted into the tree of judaism. Rom 11:17 I do not condsider myself a perfected jew. Only Jesus was that.
Jews have always accepted converts from the Gentile nations. Uriah the Hittite, Rahab, Ruth, and a few others I cannot remember off hand. The early Christians had a great discussion over whether a person should first become a Jew and then a Christian. Paul essentially said “come as you are, don’t change a thing”...............
Jesus was born, lived, and died a Jew. He followed the laws of Judaism and preached the laws of Judaism.
One who supports the tenets for which Jesus is reported to have stood is liking Judaism. If Ann Coulter were logical, she would deduce that the world would be better if everyone followed Judaism.