Hey guys, I'm John, and I know no one here really gives a crap about my person opinion.
Though I, as an Atheist, was humbled by the words of Brook Reeves of the deathcore band, Impending Doom, at one of their shows, when he said something along the lines of "I don't care if you hate me or my music. I love you like my brothers and sisters and our Lord loves you, even if you don't believe in Him or hate Him."
I took offense to the sketchy looking kids in the crowd yelling "Hail Satan!" and "Your God is fake!"
I think it's all a matter of negative versus positive emotions.
A lot of idiots hear preaching and get offended because they feel like the preaching party is being oppressive, when it's only their intention to enlighten you. If you are someone who does not liked to be preached to, then learn to see the preaching in a different light.
Any preaching I've heard from bands has always been something positive. Though I don't believe in what they do, I appreciate the love they spread, or try to spread.
If I saw a band that said "all those who don't believe will burn in the fiery depths of hell." though, I'd be offended, because that is negative the amount of dB that silence measures up to.
tl;dr Opening your mind to the point that you don't take offense to kind gestures of someone who has opposing beliefs is a cool guy who doesn't afraid of anything. If what they're saying is negative, ignore it.