Camille Paglia asserts:

Marriage is a religious concept that should be defined and administered only by churches.

This is a very strange reading of Catholic history and American history. Marriage was not a sacrament until the thirteenth century; many Protestants, most famously Luther, denied its sacramental quality through the sixteenth century. The first marriages in America were civil, not religious in nature:

When the Pilgrims landed at Plymouth in 1620, among the first things they did for the well-ordering of their new commonwealth was to institute the Dutch custom of civil marriage with which they had become familiar during their long sojourn in the Netherlands.

The Dutch made civil marriage the law of the land in 1590, and the first marriage in New England, that of Edward Winslow to the widow Susannah White, was performed on May 12, 1621, in Plymouth by Governor William Bradford, in exercise of his office as magistrate.

Now it is true that the churches have conflated civil and religious marriage ever since and this has become part of the messy civil-religious aspect of marriage in contemporary America. And Camille, as usual, has a point: a cleaner solution would be civil unions for everyone, gay and straight, with everyone also free to marry subsequently in a church or synagogue or mosque or temple of their choosing. But given the practical fact that no one is ever going to persuade a majority of Americans to abandon civil marriage as an institution, this is practically speaking what the marriage movement is fighting for. Civil marriage for all; religious marriage for all who want to supplement it with God's grace. Why is that so hard for some people of faith to grasp? Why are their marriages defined not by the virtues they sustain but the people they exclude?