Question

if muslims conquered the christian's holy land in the 600's, why did it take until 1095 for the christians to take the land back

Answer 1

At first the Christians weren't paying attention. They were fighting among themselves.
Even the Crusades were not a united Christian effort. It was more like the Pope trying to exert power over western Europe. The results were disastrous.
The Muslims were the civilized people of the time. The Crusades were the barbaric invasions.