I am honestly not knowledgeable in other religions to answer a definite yes or no. What's it say in the Quran? How do Buddhist feel about it? What about other religions such as Hindu? It would seem, for the most part, however, that christians are a huge group against it. So, from a layman's POV, I would say that christians continue to be a catalyst in the war against gay marriage, or gays in general.
Disclaimer: I am only responsible for what I say, not what you choose to understand.
