This article spells out very clearly what the Christian position is on the institution of marriage and the inclusion of same-sex marriage. In my opinion, it seems well reasoned and far from being homophobic or filled with hatred.
http://www.frc.org/index.cfm?i=IF03H01&f=WU03L06
There are two key reasons why the legal rights, benefits, and responsibilities of civil marriage should not be extended to same-sex couples. . .
(Two reasons are listed in the article.)
. . .So--what IS marriage, then?
Anthropologist Kingsley Davis has said, "The unique trait of what is commonly called marriage is social recognition and approval ... of a couple's engaging in sexual intercourse and bearing and rearing children." Marriage scholar Maggie Gallagher says that "marriage across societies is a public sexual union that creates kinship obligations and sharing of resources between men, women, and the children their sexual union may produce."
Canadian scholar Margaret A. Somerville says, "Through marriage our society marks out the relationship of two people who will together transmit human life to the next generation and nurture and protect that life."
Another Canadian scholar, Paul Nathanson (who is himself a homosexual), has said, "Because heterosexuality is directly related to both reproduction and survival, ...
every human societ[y] has had to
promote it actively . ... Heterosexuality is always
fostered by a cultural norm" that limits marriage to unions of men and women. He adds that people "are wrong in assuming that any society can do without it." [emphasis in original]