Simplify the following text for a Grade 14 native English-speaking person.
Original: Post 1965 Immigration was mostly Muslim , and unlike their Chrisitian counterparts they faced a somewhat greater difficulty in assimilating because of their Islamic faith and the `` back to the roots '' \/ anti-assimilationist trend that gripped America in the 1960s and 1970s .
Simplified: After 1965 Immigration was mostly Muslim , and unlike their Christian counterparts they found it a bit harder assimilating because of their Islamic faith and the anti-assimilationist trend in America of the 1960s and 1970s .