Religion has been at the core of a few differences of opinion in my greater family.
For example: my wife's family is Catholic and they wanted us to be married in the Church by a Priest. I, being opposed to the entire concept of organized religion, argued in favor for a civil ceremony.
Ultimately we found middle ground that satisfied everyone's criteria.
We were married by a Justice of the Peace, but one who had been convicted of molesting young boys.
Moral: If you look hard enough there are always ways to reach peaceful solutions to religious conflicts.