The concept that demographic factors don't confer favored status upon somebody is a pretty basic Christian teaching, but many Christians are still gonna be loathe to condone same-sex marriages. Equality between men & women is tricky: men & women can be seen as equal in Christ, but they can also just as easily be seen as having different roles to play in the life of the church.
I just wonder how people can argue that gender alone can determine them having different roles to play in the church. It shouldn't matter more than a person's skin color, which is not at all.
Men and women were ordained to complete each other by joining as one flesh and forming a household together. C.S. Lewis compares this to a lock and a key. The sexes are different, and this difference reflects God's intended purpose for human sexuality, which as all parts of human life is inextricably linked to the Church. There is simply no comparison to skin color here.