Seriously, I ran into this, as a pagan, with undercover Christians. I seriously thought that all Christians were the Enemy, because I'd never met a genuinely nice person who turned out to mention that they were Christian.
Now I've got Darkside, Dawn, sionainn, kellinator, wiredferret, theferrett, and others who have proved otherwise to me.
Religion and sexual orientation isn't generally obvious on one's skin the way race often is. It's up to us to make it obvious. Unless the prejudices of one's family, friends, and co-workers are stronger than their established liking/respect for you, they may well take it in stride. (Two notable exceptions: when an underage teen declares their sexuality, a responsible family member may feel it their duty to re-guide a clearly misguided youth; when one's co-workers already dislike one, being of a religion/orientation they don't like either is likely to make things worse rather than better.)
I have some Very Visible buttons on my Purple Hat, and I'll be wearing that, now that it's cool enough.