Get the churches out of marriage.
Marriage has historically always been a legal contract uniting two (or more) people, and not necessarily with consent. The function of the religious aspects of marriage are only to reinforce the seriousness of the legal contract. Historically marriage was used to share property, to end wars, to settle bets, and to buy goods. The history of marriage is property management. What part of that is religious?
That most marriages begin in a church does not make them a religious institution. Voting and town halls often happen in churches, yet no one seems to be demanding we get the government out of either of those and let the churches handle them. The argument that marriage should be left to the churches is an argument rooted firmly in historical ignorance. The church has no claim to marriage.
AC gets no resepct.