Conservatives were against slavery (Democrats were for it), and against communism (Democrats were for it, and adopted the platform).
I”m not sure you can really argue this out either way. It is becoming clear that the postmodernist movement is both false and dangerous, but the democratic party, and liberals practice it as their social religion the way that conservatives practice the cult of the revolution.
I can’t really address an issue of this scope here, but conservatives are decisively not always on the wrong side. The conservative strategy simply requires that you achieve something through merit not by force. So whatever you wish to accomplish (gay marriage) will be successful once you’ve demonstrated that you’ve ade your case and convinced the majority. This is how they work.