Boy howdy, Christian culture does not like the idea of gay marriage. They really, really, really do not. Christian culture feels strongly that legalizing gay marriage would hurt the institution of marriage and that it would be a shock to our fundamental understanding of human social relations and institutions. They also feel that legalizing gay marriage would cause God to bring his judgment against America.
Dr. James Dobson, who has been referred to as “the nation’s most influential evangelical leader” by Time magazine,  also made this statement on the subject:
“Indeed, those charges are already being leveled against Christians who espouse biblical values. How about group marriage? Or marriage between daddies and little girls? Or marriage between a man and his donkey? Anything allegedly linked to civil rights will be doable, and the legal underpinnings for marriage will have been destroyed.” 
The possibility of donkey marriage becoming legal is terrifying to people who hold moral conventions close to their hearts. But Jesus did not endorse morals or politics. Jesus endorsed love and relationship. In particular, he endorsed showing unmerited favor (i.e., grace) to members of society whom the Pharisees deemed unsavory (i.e., tax collectors and prostitutes. Do homosexuals fall in this category?). Making same-sex marriage legal would mean Christians would have to relinquish some political and moral control and trust the issue to God. It is quite a conundrum for the Christian culture, indeed.