Why I'm Still a Christian

[Jenny A]

If the government was out of the marriage business, then everyone would have the same status under the law. We could all enter into the same civil contract. We've made marriage into a legal contract, but that wasn't so in the beginning. To a christian, marriage isn't making a legal contract, but rather committing ourselves to each other, which needs no sanctioning from a civil authority. The legal contract isn't the marriage, but I also understand the need for a legal contract to protect the interests of the couple and children involved.

emphasis mine

Marriage existed long, long before there were Christians. And it exists in non-Christian societies. Christians have no right to a monopoly on the word marriage. I am married, and it is a commitment to each other as well as a set of legal rights and obligations. But it has nothing to do with god.

Call yours "holy" matrimony to distinguish it from civil matrimony if you like. Holy is a fine religious work. Or call it marriage before god. Or any other religious appellation you like. But marriage is not a religious word.