Re: Assumptions based on what religion you are.
I'm forced to listen to conservative talk radio, and one of the hosts I think made a rather good point (though not the one he was intending). He was talking about religion in politics, and how some people think it should be completely divorced when it comes to political candidates. He argued that no, people should care about the religion of candidates, since it gives insight into their character. I have to actually agree with that. What religion someone is can be very useful in determining what values they have (or lack thereof).
The problem here, of course, is that homophobia is considered a "value" in much of mainstream christianity. So, while I do agree it's a bad move to assume any particular christian is homophobic, I certainly think their being christian is worthy of suspicion of it. In regular conversation I'd probably default to "not homophobic" just to give people the benefit of the doubt, but I would ask questions if I cared to know about someone's character, such as if they were a political candidate.
So, when it comes to religion and politics, if you hold different views from the mainstream ones of your religion, you are of course going to have to explain your views multiple times. Inductive reasoning states you probably have the mainstream views, otherwise.