My own opinion, for what it’s worth, is that this issue of gay marriage has overtaken public consciousness in the last few decades at a rate faster than the Church has been able to generate new and fresh arguments for its position.
For me no argument presented here was persuasive.
(1) The state’s definition of marriage is detrimental to the species. Whole laws cannot be based on a conjecture like this. What compelling reasons and data do we have to believe this? It seems to imply that the legalization and recognition of same-sex marriage would itself cause a lower rate of procreation, but I can’t imagine a reason to believe this.
(2)Anal sex is detrimental to human nature. Those who support gay marriage could argue in response either that (a) it is not necessarily physically harmful, but rather merely risky, and it does not follow from something’s being risky that it should be absolutely avoided; and (b)Anal sex is not inevitable in a gay relationship, certainly not between women, but also not that between men.
(3)“Gay marriage attempts to redefine something that is by nature contrary to it.” This argument is not persuasive from a pluralistic, secular point of view, in my opinion. It is one thing for the Church to say: sacramental marriage is between man and woman. But on what grounds could it say that a society is not able to change the conditions under which people marry in the civic sphere?
I am a Catholic. I want to remain faithful to the Church, but I admit I am quite disheartened by the lack of persuasive arguments presented here. We should pray that God may enlighten our minds to better advance the Church’s vision.