“Not even remotely Christians”
I take it you are sinless and in a position to judge that.
The act of cohabitation is unchristian and ungodly because it takes the all too common and yet grave sin of fornication and it establishes it as a day-to-day state of being. It’s not just sin, but living in open sin. In most cases there is the aggravating factor of fraud involved, and even worse, repeated child sacrifice.