I'd be skeptical about believing anything from a "Jew for Jesus". If they can't be honest enough to just call themselves Christians, why should they be believed on any other subject?
??? So if you're Irish and you become a Christian do you cease to be Irish?
Jews for Jesus ministry/outreach is to fellow Jews. They share the gospel of Jesus Christ in hopes of bringing their other Jews to a saving knowledge *of* Jesus Christ. I've been aligned with the group since 1976.