Carlin's content is frequently critical of religion, specifically Christianity. Carlin was raised as an Irish Catholic and attended Catholic school. He alludes to "losing his faith" when he'd reached 8th grade.
In one routine called "Religion is bullshit", he claimed to worship the Sun, "because I can see the Sun," and to pray to actor Joe Pesci, "because he seems like the kind of guy who can get things done," adding, "The prayers that I used to address to God, and which I now address to Joe Pesci, both get answered at pretty much the same rate: fifty-fifty".
Much of Carlin's humor involved language and social commentary. In one of his most famous sketches, Seven Words You Can Never Say on TV (or "Filthy Words"), he combined the two, pointing out that a word that means the procreative act, the beginning of life, cannot be uttered on TV, while "murder" can. The sketch was a focal point in an FCC complaint against Pacifica Foundation FM Radio for (ironically) airing the sketch on public radio in 1973. The Supreme Court weighed a 5 to 4 landmark decision in favor of the plaintiff in 1978.