Obama on gay marriage?

Obama’s public stance as the President has been anti-gay marriage, pro-civil unions. He said this is due to his christian religious beliefs.
obama interview
and he was quoted in the Chicago Daily Tribune, saying, “I’m a Christian. And so, although I try not to have my religious beliefs dominate or determine my political views on this issue, I do believe that tradition, and my religious beliefs say that marriage is something sanctified between a man and a woman.”

But despite his religious beliefs he still supports repealing the Defense of Marriage Act.

But, it is my understanding that prior to his presidential career, i.e. during the time he was running for the House, and when he served in the senate, he was perfectly fine supporting gay marriage.
see this link

Do you think he honestly disapproves of gay marriage (for religious reasons), or do you think this stance is a political move since during the campaign he advocated “working across the isle”?

I am confused. Please help!
Since I can’t ask Obama himself, I turn to you, oh great flutherites.