religion

Who should decide if marriage is strictly between a man and a woman? The government? The Church? We have a multitude of religions in the United States. We also have atheists and agnostics. If  the church were to decide who can marry, then where does this leave the atheists and agnostics? If the government decides, then what principles do they base their decision?  If they base their decision on christian values then is this not showing prejudice against the other numerous religions that may find laws based on christianity alone offensive?