Looking at the progress of gay marriage around the world, there are many counter-intuitive cases. The Scandinavian countries, so notoriously liberal, who did take some of the earliest steps (first civil unions in the world were in Denmark, 1989 iirc), but then after that were quite slow to get around to actual gay marriage. Spain, almost equally notoriously Catholic, which passed it very fast back in 2004, and did encounter a considerable amount of protest, but really not as much as many would have expected - especially compared to the very secular France, passing the law a decade later and apparently having a lot more protest against it. The case of Hawaii that I mentioned earlier. And so on.
The cases of conservatives using gay marriage as a political weapon, most notoriously in 2004, are well-known, but in a sense it's also a liberal weapon in many cases. The Economist wrote an article not long ago about how the British youth was becoming so notably liberal (in American-speak, read "libertarian" ), and their main argument seemed to be that the youth was pro-gay rights. As much as I support gay rights myself, I couldn't help but wonder if people aren't becoming too inclined to reduce someone's entirely outlook on the "social" issues in politics to that one question of being pro or against gay marriage, making it a litmus test so to speak. After the Brits legalize gay marriage in a year or two, perhaps the Economist will realize that they were making some dangerous over-simplifications.
So you're definitely on to something when arguing that it's not so simple and that you sometimes have to push, and sometimes just let things develop. In any case, in the West (including Latin-America) at least, time is definitely on the side of gay rights. Now, the rest of the world... that may be a different and subtler story.