It is culture not religion texts that determines morality. It is culture not religion that causes some people to be permissible of divorce but not gay sex. Both are against the bible among most interpretations yet culture causes people to use the bible as a source of moral authority with one but not the other.

Furthermore people of different religions including ones not connected to judaism, christianity, and islam can be against gay marriage. Furthermore you can be very devout with region, not very devout, or even athiest and still be against gay marriage.

It is the culture not the religion.