My view is that we should try to disentangle what has historically been the issue of the word "marriage," which has religious connotations to some people, from the civil rights that are given to couples, in terms of hospital visitation, in terms of whether or not they can transfer property or Social Security benefits and so forth. So it depends on how the bill would've come up. I would've supported and would continue to support a civil union that provides all the benefits that are available for a legally sanctioned marriage. And it is then, as I said, up to religious denominations to make a determination as to whether they want to recognize that as marriage or not.-Barack Obama, 2007 HRC/LOGO debate on gay issues Aug 9, 2007
To sum up: He believes in a total separation of church and state, saying that the government should grant "civil unions" to any couple, and churches can grant "marriages" as they please.
Which.. y'know, makes sense. If religious/bigoted assholes want to get the panties in a twist over the term "marriage" then fine, whatever. The legal protections that the civil institution offers should be available to all tho. Nice solution if you ask me.