This topic reminds me of something a friend's mom said back in high school: "I have black friends, but I think races should stick to themselves when it comes to relationships."
Gay marriage is in the same spotlight as interracial marriage once was (and sometimes still is). If you are friends with someone who is gay, but you don't believe they should have the same rights as you, you are against gays.
My lesbian friend Joey said it like this: "I don't want to get married, I just want the right to."
If you don't believe that a group of people should have equal rights, the same rights you have and probably take for granted, then yeah, you're prejudice. If I said something like, "I have white friends, but they shouldn't have the right to vote like I do," people would think I was a racist.
This is the same concept. If you have gay friends, but you believe that they shouldn't have the right to get married like straight people do, then you're a homophobe.
I've gotten plenty of arguments for being against gay marriage:
Because marriage is and has always been simply defined as between a man and a woman.
That is a Christian concept. But marriage predates Christianity. Plus, in the United States, there is supposed to be a separation of church and state. Which means keep the Bible out of the law.
If any straight couple can get married at a drive-thru wedding chapel in Las Vegas, what is it about gay marriage that supposedly destroys some religious freak's sense of the sanctity of marriage??
Marriage is not based on religion. Or at least it shouldn't be. If you want to get married in a church or a synagogue or a park, that is your prerogative. If you want to be married by a priest, a minister, a justice, or an Elvis impersonator, that is also your choice. But don't fucking preach your shit to everyone else like it was some divine mandate that everyone must follow.
