Being Jewish is a broad term. Just as Christianity and Islam have lots of sects that have little in common, so does Judaism. You have to believe only 13 things:
1. God exists.
2. God is one and unique.
3. God is incorporeal.
4. God is eternal.
5. Prayer is to be directed to God alone.
6. The words of the prophets are true.
7. Moses was the greatest prophet, and his prophecies are true.
8. The Torah was given to Moses.
9. There will be no other Torah.
10. God knows the thoughts and deeds of men.
11. God will reward the good and punish the wicked.
12. The Messiah will come.
13. The dead will be resurrected.
Note that that list is incompatible with Christianity.
Many Christians wouldn't have much of a quarrel with that list. Christianity was inherent in the message of Judaism before it got hijacked by rabbinism. The physical body of Jesus is something that many Christians view (on biblical grounds) as a tent that was created by God for God to occupy, rather than being inherent in God by nature.