Marriage is a sacrament given to us by God. If we lived in a theocracy that might matter more, if it is true in the first place.
Marriage BY THE CHURCH might be a sacrament given by God. Observe that people who do not believe in God also get married, as do those who believe in whole bunches of Gods.
But that is not the issue here. We are talking about civil marriage, which is clearly performed by the state, and this has no effect on whatever degree of holiness you place on a church wedding.
Apples and oranges, apples and crabapples, but different things.
As BSB said, the culture wars are over and your side lost.
and again, what possible harm to anyone's marriage could it be if Adam marries Steve in the County Court? You have yet to answer that question, haven't you? I suggest none, as in bupkiss, nada or zilch.