Obama said that while he does not believe in gay marriage, he does think the state should allow civil unions that allow a same-sex couples to visit each other in a hospital or transfer property to each other.

"If people find that controversial then I would just refer them to the Sermon on the Mount, which I think is, in my mind, for my faith, more central than an obscure passage in Romans," Obama said.

http://blog.christianitytoday.com/ctliveblog/archives/2008/03/obama_cites_ser.html

check out video
http://www.youtube.com/watch?v=J6oh4gL51U4