Redefine marriage as a religious union, and define a civil union as a legal union.

Many of those in the religious community are concerned that gay marriage will corrupt their idea of marriage. We propose that marriage be a purely religious union, completely separate from government. Civil unions however will be required if you wish to file taxes together and so forth. Civil unions will be granted to people not based on their sex, but their need to be legally united for puposes other than religion. Instead of being married, one could just be "united" with another person.