Ok for example I don't go and find Christians and try and get them to convert to whatever the fuck I believe in, however a big part of many faiths is getting people to convert to your faith while you believe other faiths are works of the devil or some such. Pisses me the fuck off, and if I don't know them I do just tell them to fuck off.
However more often than not, having a lot of christians in my extended family I have to be polite when some relative tries to sway me or just talk to me about why jesus is so great. My girlfriends parents are the worst, every time I talk to her step dad its jesus this or marriage that

Not only that I can't even sleep in the same fucking room as her if we stay at their house (which I've only done once and I slept on the fucking lounge floor, and no I didn't get to defile their house with illicit sex either :'().
Hence I think I have many more rights to diss on religious people as they persistently invade my personal space with their bullshit. Can't they just be content with saving their own souls? I like mine dirty.
edit: in other words I don't care if they think I'm a heathen. I do know christians who I'm happy to be around and I don't treat them like fools (even though I think they are) so long as they keep their religious spoutings away from me.