I prefer the less romantic label that is more accurate, 'homosexual' marriage. American Senator Ted Cruz has called gay marriage the greatest threat to religious freedom in American history; and the reason is because (upon the possible national legalizing of homosexual marriages) the social political leftists will then demand Church sanctioned homosexual marriages, which cannot be provided by true orthodox churches. A priest or minister cannot do what God forbids. This is the position on abortion as well. Secularist view Christian churches as democracies, and many Protestant ones act like that. But the Catholic Church has never made a deeply fundamental change in over 2000 years because God does not change his mind. Yes, the Old Testament contains things (like harsh punishments and slavery) that are not accepted today, but the coming of Christ and his sacrifice for the sins of mankind was a game changer. That significant series of events that Catholics believe to be the most important in history made many old, accepted (and seemingly barbaric) conventions in the Old Testament null and void.
In both cases, homosexual marriage and abortion, the modern conversation avoids the obvious natural issues of 'acts against nature' that those acts were once commonly so labeled. That label was once the legal issue in the case of the marriage issue and perhaps it was with infanticide as well. While the abortion issue (a form of infanticide) should need no explanation as an act against nature, the homosexual issue is pretty obvious as well. Had there been a human owner's manual, it might have said (with respect to sexual acts) "At the appropriate moment, Insert tab A in slot B." Obviously, to all except the most challenged thinkers, in most circumstances, only men have tab A and only women have slot B. All other options seem to be due to the participants more or less bending the rules for their own self-centered gratification. I'm not here to comment on the bedroom variance of activities between correctly heterosexual married couples or the morality of said variances. But it does seem that the non-existent yet 'understood' manual sets the minimum base requirement as intended by the designer (Creator) of the system and equipment.
It seems as well that humans have failed through the ages to 'read' the manual, as we commonly fail to do with all equipment that comes into our possession. During certain ages of history, we seemed to have throw the manual away_ ancient Greece, Imperial Rome, early Polynesia, many others, and now. But, for Christians, two other eternal truths echo comfortingly through time_ Christ told us we would always be the abused and marginalized minority (so we can handle it), and the end game unconditionally favors us if we fight the good fight without significantly faltering. One can even cave under extreme torture and coercion and still win. The cards, in the ultimate game against over whelming odds, are actually stacked (unfairly perhaps) in our favor. We actually win if and when we lose, while our opponents inherently cannot win; and the stakes are for all time, which they don't believe in. It is our reward for the whole 'marginalized minority' thing. I'd gloat, but that is against the rules as well.