From the National Catholic Register:
Q: When we defend marriage between a man and a woman, our opponents say we’re just imposing our religion on everyone else. What’s the answer to that?
Bishop Cordileone: This is not a matter of religion. This is how every society has understood marriage in all of human history. The truth is: They’re imposing their new idea of marriage — an idea no society has ever had before — on everyone else. This is a very serious social experiment that will have dire consequences.