I haven't seen it, but it sounds like the the "moral" of the story it would have been better for Kyle to find some joy in Cartman's good fortune rather than his misfortune. I strongly agree.

Kyle fell into what Ellsworth Toohey promoted and what Gail Wynand got sucked into at the beginning of Fountainhead: They can't stand to see people going out and succeeding in honest endeavors. Wynand seemed to fear that anyone else's success / self-determination was one step toward his childhood nightmare of constantly being dismissed with "You don't run things here!" Toohey's motivations were less clear. He just liked sabotaging people, perhaps to make them get on board his worldview of misguided charity.

Kyle reminds me of Wynand. When he's in his fifties he'll drive through the northwoods to meet a lover and have a change of heart.

I saw it as demonstrating a very simple human trait: misery loves company.

Kyle felt abandoned by God, since he was miserable and Cartman wasn't. Just as soon as Cartman was as unhappy as Kyle, Kyle's faith in God was restored....

Keep in mind that South Park is all about sarcasm.

Do you mean like you shouldn't look to others success or failure for happiness?

I thought when was a little more interesting than where. :P