i have no problem with it, because regardless of whatever religious beliefs i may or may not have, marriage is not just a religious institution in our society - there are legal rights that it is essential for two people in a committed relationship to be able to exercise if they wish to live together, adopt children, have joint bank accounts, health insurance, etc.
absolutely churches have the right to decide which marriages they officiate and recognize, but we can't let them decide who is and is not delegated legal rights. if two consenting adults of legal age want to be married and commit their lives to each other, it is not the law's place to say that they cannot.