Give the term "marriage" to the church. Remove it from all laws. Both homosexual and heterosexual couples will have "civil unions" in the eyes of the state. If you want a union in the eyes of God, go to a church. If you want a union in the eyes of the state, go to the courthouse. That pretty much puts an end to any of the religious arguements used to oppose same-sex marriage. The whole freedom of religion thing already takes care of the moral arguements against it.