There is no doubt that America is a Christian nation, because the majority of its citizens are Christians. However, neither Supreme Court Justice Clarence Thomas nor the New Mexico Center for Family Policy seem to be able to recognize that the government of America is a secular, not a religious, one (Op-Ed here).
The First Amendment states clearly that “Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof …” Therefore, our government has nothing to say about religious marriage. However, there has also long been a secular institution of civil marriage, which is not religious.
Hundreds of years ago, when all governments conflated power with religion, there was no distinction between religious and civil marriage. With the not so recent advent of secular governments, apparently unnoticed by Thomas and the NMCFP, a distinction arose between the two. While many marriages are religious, all recognized marriages in the United States are civil. The First Amendment requires that they must be and must always have been.
American governments have sensibly continued to accord recognition to religious marriages as also being civil marriages, but non-religious marriages such as common-law and those before a Justice of the Peace are also recognized. The distinction between civil and religious perhaps first became apparent with the advent of divorce, forbidden entirely by some particular sects, which only allowed for annulments, for example. Our governments have carefully never said anything about divorces of religious marriages, but only enacted statues regarding divorces ending civil marriages, which may or may not have also been religious.
The interest of a secular government in civil marriage has primarily to do with property rights, inheritance, responsibility for children (if any) and, in some matters, implicit power of attorney. Religion and indeed, love, are irrelevant to the government, as they must be, to avoid infringing upon our rights to personal freedom — to life, liberty and especially in this case, the pursuit of happiness.