If, as I said, I was approaching the question from the perspective of “what would constitute a valid reason to some random single person”.
If we assume that this random person truly believes that their religious reason for opposing gay marriage is a valid one, and we further assume that they might also believe that their reason meets all of your criteria, said reason could, from their perspective, be seen as a valid one.
Granted, it would seem unlikely to be a logical argument in that case, but it is also possible – after all, not all people come at things from the same angle…
Further, such an argument would be highly unlikely to stand up to any kind of examination by one’s peers, or for that matter, anyone who does not hold the belief system that supports it.
However, it does seem possible, while extremely remote.