then why can't a Messianic Jew, who believes in G-d, still be considered a Jew? All Jews descend from "Israel". Messianic Jews believe in the G-d of Abraham, Isaac, and Jacob but believe "Echad" is plural & Yeshua is the Messiah (and a part of G-d). They don't think Yeshua replaced G-d. In the "Christian" Bible it says Yeshua sits at the right hand of the Father.
from the article: Reform rabbi: Israel's pluralism threatened by new conversion law