Who was the first Jew in space? No, not Judith Resnik; she was the first Jewish American and the first Jewish woman.
Judith's first flight came in 1984 (two years before she perished in the Challenger disaster). But the first Jew to venture into the final frontier was Soviet cosmonaut Boris Volynov, who went into space 15 years before Resnik: January 15, 1969.
And if not for his heritage, Volynov could have gone even earlier. Scheduled to fly in 1964, Soviet command pulled him off the mission when they found that that Volynov was... that's right, Jewish. Replacing the mission commander three days before the flight just because his mother was a Jew? Welcome to the Soviet Union.
Somehow, Volynov got over his... "handicap" to go to space twice, in 1969 on Soyuz 5 and 1976 on Soyuz 21. Gotta love the Soviets' open-mindedness, right?