I remember that simpsons episode, the most disturbing part to me was the extremely harsh anti-catholic bigotry by Marge Simpson, and it was never repudiated.
She just out and out lashes out at catholism and rips on the church in some of the most mean spirited manner that no other episode displayed.
Matt Groening knows that he won't get shot for it. Let's see him even begin to make fun of Islam. Just ask Pym Fortune what happens when you do that...Oops!