On Joan of Arcadia, God appears to Joan in the guise of regular people. The people aren't delusions--everyone else can see them as well. It's unclear (to me, at least) whether they are people who exist when God is not speaking through them, or whether they exist only when God needs them as mouthpieces. Either way, though, every conversation Joan has with God is one with another person. My personal favorite God is Goth God (left), followed by Joan's original and probably most common God, Cute Guy God (right). Some of the God are irritating (Old Lady God and Little Kid God both bug me), some you forget as soon as you see them (the episodes are full of one-off Gods as delivery people, cafeteria workers, substitute teachers, etc.). Often, Joan mistakes people who are not God for God, based on what they say to her.
Maybe I'm dense, but I like a metaphor that hits me upside the head. I'm not sure I believe in God (nor am I sure I don't), but it's difficult not to believe in other people, given that they are overtaking the planet like cockroaches. On the show, God mostly gives Joan assignments, most of which are difficult for her to complete. God gives vague advice, rarely answers questions, and is generally kind of a pain in the ass. The non-God people she's surrounded by--her family and her friends--are usually more helpful to her than God, at least in seeing the results of her wacky actions. Yet she gives them none of the acquiescence she gives her many Gods.
Maybe that's the point. Maybe instead of looking for a higher power in a Church or even inside ourselves, we should look around us. I'm going to try to do a better job of listening and watching and paying attention to what other people are telling me. You never know, there might be God in there.