The Bible describes only the worst that a marriage can be, but never defines what a marriage should be. - Aron Ra

I don't believe in marriage, myself. It's an arbitrary human concept with no reality beyond that. It isn't always necessarily romantic; it is often political. Even if you believe in God, and swear to love one another for better or worse, till death do you part, none of that is assured. In fact, evangelicals are statistically more likely to get divorced than people with no religion.

I was a young man in the ’80s, and I was into medieval weapons, Harleys and Heavy Metal. I even played D&D back when that was supposed to induct players into real-life witchcraft. So I remember all the ridiculous superstition surrounding the secret meanings of ear piercing, the pseudo-paganism of Procter & Gamble, the seemingly Satanic messages in back-masking, and the allegedly suicidal insinuations of some metal albums. I attribute a lot of that to the fact that atheism didn’t have any appreciable presence back then. In those days, if you didn’t buy into Christian dogma and were openly critical of it, then you were a witch. You were either a neo-pagan or (more likely) you were Satanic. The latter would be applied regardless how you might prefer to identify. To my cultural experience, there was no such thing as a skeptic as that is known today. Back then, skeptics were considered cynics who refused to open their minds. It must have been a great time for paranoid Christian conservatives. They actually like Satanists a lot more than atheists. Because Satanists not only play the Christian game; they give Christians the moral high ground. Whereas atheists piss everybody off by pointing out that it is a game and that every believer in any religion is just pretending.

We can tell murder is wrong because we have objective criteria by which we can determine for certain whether murder is wrong, and we can do that regardless of what mood the gods are in nowadays. There has to be an objectively verifiable reason why something is moral or immoral, or else no one could know whether it is, including God, since the Bible has Him changing His mind all the time. Without that criteria, you couldn't know what is moral or immoral either; you just have to trust whatever the people said who pretended to speak for God.