There are two aspects to marriage: the legal and the spiritual. Marriage is more than a social convention, like being "best friends" with somebody, because heterosexual marriage usually results in the production of children. Marriage is a legal institution in order to offer protection for women and children. Women need to have the freedom to devote their time and energies to be the primary nurturers and caretakers of children without being forced to be breadwinners as well. God's plan is that children grow up in families who provide for them, protect them, and wrap them in security. 

           Because gay or lesbian couples are by nature unable to reproduce, they do not need the legal protection of marriage to provide a safe place for the production and raising of children. Apart from the sexual aspect of a gay relationship, what they have is really "best friend" status, and that does not require legal protection. 

            Of course, a growing number of gay couples are seeking to have a child together, either by adoption, artificial insemination, or surrogate mothering. Despite the fact that they have to resort to an outside procedure in order to become parents, the presence of adults plus children in an ad hoc household should not automatically secure official recognition of their relationship as a family. There is a movement in our culture which seeks to redefine "family" any way we want, but with a profound lack of discernment about the long-term effects on the people involved. Gay parents are making a dangerous statement to their children: lesbian mothers are saying that fathers are not important, and homosexual fathers are saying that mothers are not important. More and more social observers see the importance of both fathers and mothers in children's lives; one of their roles is to teach boys what it means to be a boy and teach girls what it means to be a girl. 

             The other aspect of marriage is of a spiritual nature. Granted, this response to the gay marriage argument won't make any difference to people who are unconcerned about spiritual things, but there are a lot of gays who care very deeply about God and long for a relationship with Him. The marriage relationship, both its emotional and especially its sexual components, is designed to serve as an earthbound illustration of the relationship . Just as there is a mystical oneness between a man and a woman, who are very different from each other, so there is a mystical unity between two very different, very "other" beings the eternal Son of God and us mortal, creaturely humans. Marriage as God designed it is like the almost improbable union of butterfly and buffalo, or fire and water. But homosexual relationships are the coming together of two like individuals; the dynamic of unity and diversity in heterosexual marriage is completely missing, and therefore so is the spiritual dimension that is so intrinsic to the purpose of marriage. Both on an emotional and a physical level, the sameness of male and male, or female and female, demonstrates that homosexual relationships do not reflect the spiritual parable that marriage is meant to be. God wants marriage partners to complement, not to mirror, each other. The concept of gay marriage doesn't work, whether we look at it on a social level or a spiritual one.