While we do have many things in common with our Jewish brothers and sisters we obviously have some major differences.
One of the major differences is the belief in Yeshua as the Messiah. The concept of believing in a Messiah is not foreign to Judaism. One of the thirteen principals of the Rambam was “I believe with perfect faith in the coming of the Messiah. How long it takes, I will wait for His coming every day.” (Number 12)
Also Messianic Judaism is somewhat of a