Hard data on the number of civil marriages performed in the United States are hard to come by. A 2003 study by USA Today found that of 18 states that kept statistics on civil versus religious marriages, the percent of nonreligious ceremonies had gone up among 14 of them, to more than 40 percent (from about 30 percent in 1980). Why should the marriage circumstances of those Americans who choose to wed nonreligiously be dictated by religion?
This is a nontrivial matter. Civil marriage is more than a couple of wedding rings and a sheet of paper. According to the National Organization for Women, married couples have 1,138 federal rights, protections, and responsibilities, including things like Social Security benefits for spouses and Family and Medical Leave Act protections.
And other aspects of marriage are not set by religious dictates. The Catholic Church, for example, does not recognize divorce and takes a deeply dim view of premarital cohabitation (both of which are arguably greater threats to traditional marriage than men wedding each other). Should the civil authority mirror those views as well?
Remove religion from the equation and the remaining bar to gays achieving civil marriage equality is societal norms. But as van Lohuizen noted, those norms have changed with startling speed. Indeed, the preponderance of polls now show majorities favoring it.
To paraphrase a wise man of old, render the sacrament of marriage unto God, but leave him out of the discussion of secular marriage, along with all of its rights and obligations.