That's not what he said. He said churches shouldn't be forced to perform it, which, in my opinion is an okay thing. Religious institutions have their beliefs and we should respect them. The problem is the state doesn't respect our beliefs, and that's what Obama was saying. The government can't force churches to do something like that, it would be unconstitutional; but the government can recognize same sex marriage (and should) based on human rights, equality, and the fourteenth amendment.