I'm talking about God and truth, neither of which necessarily have anything with whatever someone wants to call "religion".
The point is that if we switch to letting any religion, which would mean ALL religions and cults, and atheist identity groups define marriage, then there would be no definition, therefore no marriage in our society at large.
Yet we all know that there has to be a body of law regarding marriage and divorce/children/property, so there we are again, a common law (or authority) defining marriage.
Modern America is a different place from the past, libertarians and liberals and immigration has destroyed our common roots and community, but we still need common laws that apply to us and protect us and our families, and as we travel from state to state.