Something to contemplate -- everyday there are dozens of gay ceremonial marriages performed by ordained clergy, though not recognized by the States in which they are performed. By your response, I take it that you're okay with gay marriage.
I'm fine with ceremonial marriages that are private contracts between consenting adult individuals. I object to the concept that these private contracts can lead to special recognition, rights or obligations imposed by the government. I'd never participate in a gay marriage, nor would I be a party to an Islamic ceremonial marriage for that matter, but the private contracts created by these are none of my business except to the extent they interfere with my rights. The same can be said of a Christian ceremonial marriage. To each their own.