[there's no non-religious argument anywhere]Yyyyeah many of the arguments in discussions on this side of the Atlantic have nothing to do with religion.
Example 1 : homosexual couples gaining access to child adoption, care, support, and other similar rights will mean there's less money and such to be used to help heterosexual couples.
Example 2 : legal papers won't be allowed to write "father" and "mother" but "parent A" and "parent B" which lessens the value and validity of heterosexual couples (it's a men-wounded-in-their-male-pride kind of thing, like "the normal way is being denied its existence").
Of course those are bullshit arguments, but they're non-religious, and they're the kind of stuff people have against gay marriage over here (I've heard two co-workers say those examples out loud).
If I struggled to the end of my determination, to the end of my way of life with my followers, if the result is ruin, then this ruin is inevitable. Grieve. Shed tears. But you cannot regret.