**Give back the land to the Christians? But the land belonged to the Jews.***
After the Jews were carried away captive to Babylon the land rarely had Jewish rulers.
Persian, Greek, Egyptian (Ptolemy), Roman Pagans all ruled over the Jews when they returned.
After the Jews revolted in 70AD, they were expelled from Jerusalem (Aelia Capitolina), but were allowed to live in the surrounding areas.
http://en.wikipedia.org/wiki/Aelia_Capitolina
When ROME became Christian, so did Aelia and remained so till the the moslem invasion.
Jews were ruled by Jews when they were conquered by Rome, and it was very Christian of them to not let Jews back into their own capital, after Rome became Christian, and to pass all sorts of restrictive laws targeting Jews. Aelia was Christian because Jews were not permitted to live there on pain of death.
In the middle ages, Jews didn’t have much to choose between Christians and Muslims. Many fled to the Khazar kingdom, which converted to Judaism.