This was despite the belief within some Muslim communities that Muhammad should never be represented visually, and doing so is a greatly offensive act. Largely composed of religious figures from around the globe (as well as the Aquaman parody, Sea-Man), the episode aired in July of 2001 to little uproar.
Stan and Kyle's role in the two episodes is set up by the events of Season 5's 'Super Best Friends,' which introduced the titular superhero team.