The thing that gets me riled up is the muddy thinking and semantics.
According to the Christian church, marriage is one of the seven sacraments. It is up to the various religious denominations individually to decide who they will and will not permit to partake of said sacrament. Any Federal law trying to restrict who can and can't partake is a de facto violation of the second amendment.
I find it very funny to have at least moderate conservatives saying they are against gay marriage but could live with some form of civil union. Seems to me they've got things backwards, since government does have juristiction over the legal aspects of domestic partnerships: benefits, taxes, inheritance, maintenance of children etc.
Actually, I think the genie is out of the bottle....and high time too! We may have to go through a period of tooth gnashing and breast beating, rather like breaking in new shoes, but gay marriage is not going away.