Long-time viewers of the show wrinkle their nose at this, but it makes sense if you think about it. Observe:
Raymond: Raymond is Sloth. Obviously. His character might be summed up as someone who wants to get home from work, sit on the couch, and watch TV. (Leaving his wife, of course, to care for the children, cook the meals, do the laundry, etc.) Entire shows are predicated on the idea that Ray not only does not help with ANYTHING at home, but hinders his wife's work as well. And even in shows where this is not the main focus, it's at least a running joke.
Debora: Debora is Wrath. She is the other side of the running joke about Raymond's Sloth-- it is that Sloth which incites her to wrath. She is not exaggerated to the point of being the type of character who flies into a rage at the drop of a hat, but she does have a quick temper. In one episode, a group of old women who don't know them THAT well conclude, "If I were Debora, I would be nicer to Raymond."
Robert: Robert, Raymond's older brother, who lives with his parents for about half the seasons on the show, then lives by himself, then lives with his wife, and in the final episode moves with his wife back in with his parents, represents Envy. One of the other characters, in mockingly summing him up, says that while others are talking about lawns, Robert's comment would be, "I don't even have a lawn, Raymond has a lawn." Raymond also has a house, a high-paying jobs, kids, and (at least in Robert's eyes) a perfect wife, which Robert wishes he had. A large part of his character is self-pity, but he often has the idea that "If I had what Raymond has, then I'd be happy," which qualifies him for Envy.
Frank: Robert and Raymond's father is the hardest to pin down, but I will call his character Gluttony. He is fond of eating, and he is fond of doing whatever he wants, whenever he wants to. Fifty years ago he might have been called a boor. He could qualify for Greed, as these two are somewhat similar sins, and he could even qualify for a sort of near-harmless, old man sort of lust, but Gluttony seems chief among them.
Marie: The matriarch of the family, Marie represents Pride. Her obnoxious behaviour and narcissism are the base of the conflict for probably a majority of the episodes. She is very arrogant and vain, also, but the closest thing I could find on our list was pride.
Now, when watching the show, you don't think of these people in such harsh theological terms. These are not evil people; they are what we would probably call decent. Yet they are sinners, as is evinced in every single episode of the show. I seem to be building up to some sort of conclusion here, but I lost it; I suppose I just wanted to point out that these characters, at least, have a strong set of moral values, even if it is sometimes an unclear set, and that (morally, at least) puts them far above much of what's on TV these days.