5ms, the difference is that someone knocking on your door isn't trying to offend you. They may do so as a side affect but that's not their motivation. This guy, on the other, clearly lives to offend. Presumably because he thinks that makes him appear clever and important.
As an aside (not really about religion but something that's been bothering me for a while), there's alot been shouted lately about people's right to offend. We do, indeed, have a right to offend (and that's wonderful because it also gives us the ability to criticise without fear of reprisal) but if you're going to exercise it purely for the sake of exercising it then you're still a butthole. I have to say, this guy comes across to me as wanting to offend purely for the sake of it.
