Anything about religion and God and belief is good territory. You can hear the sphincters tighten as you begin. "Let's see how he's gonna handle this!" I try to sense and know where the line is. Where the line we're drawing these days is. And then I deliberately cross it. And I try to bring them with me across the line and enjoy the experience. I do it in service of ideas. It's not just for its own sake, to bother or annoy or shock. I have ideas and though the logic sometimes is nicely twisted, there's a good structure underneath it. I use the language or the topics to vent this personality of mine that's out of step and really doesn't buy all this stuff...If all I ever do for the rest of my career is fill up coffee houses on a Friday and Saturday night, I'll be happy. And when you're not reaching real hard for something — I think when you're not pursing something relentlessly, I think it may come to you a little more easily.
A couple of great examples of Carlin bringing people with him over the line: His "Fuck the Children" bit...
...and this great rant on Politically Incorrect post-Katrina.
Here's a great speech CK gave honoring Carlin [via Laughspin].
There were similar themes in Goodbye George Carlin, a piece CK wrote about Carlin after he died.