The Simpsons is and was the show that has the exploration of religion and belief at it's core. They go to church. Lisa embraced Buddism and Bart earned his soul. But again, thirty years ago they were attacked by some for being 'unChristian
I thought of The Simpsons last night when thinking about this thread, yes! Even the episode with Bart converting to Catholicism, which came at a fairly gimmicky time in the show's history, is a lot better than a similar plot would probably be in most other shows. And of course "Homer the Heretic" is an all-time classic, as is "In Marge We Trust".
My parents had never let I or my brother watch The Simpsons when we were kids (think 2000s). When I finally took it on myself to explore the canon last summer, I was struck by the show's religious content. Watching Bart feel like he wouldn't enter Heaven because he sold his soul had me internally screaming "What did they think they were 'protecting' us from!?"
Of course there's also, as Andrew points out, the episode where Lisa converts to Buddhism, which deals with the subject very well (including presenting Reverend Lovejoy as checked-out and hypocritical but in a sympathetic and even tragic way, something that the episode has in common with "In Marge We Trust"). This despite, again, coming at a period in the show's history where its credibility on subjects that
weren't religion was already depleting fast; it of course has the Richard Gere cameo, increasing reliance on celebrity cameos having been one of the canaries in the coal mine for the show's decline.