I'm not an Orthodox Jew, but I'll be happy to answer.
Jews are better off in Judaism. Period. A Jew who converts to another religion is abandoning the everlasting Covenant God established with our people. It is irrelevent whether it is Catholicism or Protestant Christianity. It is a cause for sadness, not rejoicing.
Being the Messiah, Jesus, the Jew, the foretold 'seed' of Eve, descendant of Noah's son Shem, son of Abraham, Isaac, and Jacob, promised One of Moses, of the line of David, is the culmination and crowning glory of all that is Jewish.
FReegards, .30.