To my mind, the greatest hypocrisy displayed by same-sex marriage opponents is their insistence - and of course they are right in this - that it is advantageous in many ways for children to grow up in a home with married parents, on the one hand, and on the other their seeming disregard for the welfare and wellbeing of the hundreds of thousands of American children living with families headed up by same-sex couples.
An estimated one-quarter of all same-sex couples in the U.S. - 22% of male couples and 33% of lesbian couples - are raising children. Until quite recently, those children were unable to partake of the legal, social and economic benefits of living in a household headed by a married couple, while at the same time society and the law, as it then existed, was teaching them that a marriage license was unnecessary. A child, straight or gay, who grows up seeing his or her parents living as a happy, loving and supportive couple without the benefit of a marriage license is less likely to feel the need to ever get one themselves.
You can't logically praise the benefits of partaking in an institution, while at the same time denying participation in that institution to millions of sane, adult, consenting citizens because the religious doctrines of your church disapprove of doing so.