(CNN) -- Nothing is sacred on "South Park."

This is a show, after all, that once painted God as a gap-toothed rhinoceros-monkey, portrays Satan as a simpering milquetoast and regularly features Jesus as a superhero -- the kind who's not afraid to ignore the peaceful teachings of the Sermon on the Mount to smite his opponents. The show has mocked Jews, Catholics, Mormons, Scientologists and atheists, among (many) others.

It's a formula that's generally served "South Park" well, allowing it to score comic points by riffing on hypocrisy while emphasizing a message of libertarianism and tolerance, and it's one that goes back to the show's beginnings, points out former Dallas Morning News TV critic Ed Bark, who blogs at UncleBarky.com. After all, he recalls, the show began as a Christmas short violently pitting Santa Claus against Jesus.

But have they gone too far this time with a depiction of the Prophet Mohammed in a bear suit?

In the beginning, it wasn't so much the religion that bothered observers but the language used by the series' pint-sized cast, he said.

"The most shocking thing back then was, you had little kids exercising a vocabulary that you hadn't heard before [from children]," he said. "I go back to the days when [the sitcom] 'Uncle Buck's' 'You suck' was a major point of contention on a CBS sitcom and everybody went crazy about 'how can they have an 8-year-old kid saying this?' And then 'South Park' ratcheted that way up."

However, the show can still ruffle feathers.

For its 200th episode April 14 -- the beginning of a two-part story that concludes Wednesday night -- "South Park" creators Matt Stone and Trey Parker decided to go all-in, creating a plot line about free speech in which most everybody the show's ever offended comes back. Among the episode's characters: the Prophet Mohammed, who is first pictured behind a black "censored" bar and later in a bear suit.

That didn't sit well with Revolution Muslim, an Islamic group that objected to Mohammed's portrayal.

According to some Muslim traditions, the visual depiction of Mohammed is not allowed.

"We have to warn Matt and Trey that what they are doing is stupid and they will probably wind up like Theo van Gogh for airing this show," the group said on its website. "This is not a threat, but a warning of the reality that will likely happen to them."

Islamic group: 'South Park' post a call to protest, not violence

Van Gogh was the Dutch director who was killed in 2004 by an Islamic extremist. Among his works was "Submission," a short film about abuse of women in Islam.

The creator of the Revolution Muslim posting said that the group only wants those offended to be able to voice their opposition in letters to the show's creators and that it did not advocate violence.

"I have no respect for a prophet or god that needs its followers to defend it by threats and murder. 'South Park' should be applauded," Andrew said on the "AC360°" live blog.

"I'm a Muslim that loves the message of the Qur'an dearly, but that is not MY Islam," Erbab added.

Parker and Stone knew what might be coming. In an interview with the pop culture and tech site BoingBoing.net during production of the 200th show, they acknowledged that Mohammed would be a character but didn't know how he would be portrayed -- or whether Comedy Central, "South Park's" network, would let them show Mohammed at all.

"If they would let us show it, that would be great," Stone said.

"We're having fun with the same fight," Parker said.

Comedy Central had no comment on the controversy, the network said.

It wasn't the first time Mohammed was featured on the show. In the July 2001 episode "Super Best Friends," he appears as "the Muslim prophet with the powers of flame," along with other religious figures -- Buddha, Moses and Mormon founder Joseph Smith among them -- who help the other "South Park" kids rescue Kyle from a cult devoted to magician David Blaine

But that, said Stone and Parker, was before September 11, the van Gogh murder and the 2005 Muslim protests over the Danish cartoons that appeared in the newspaper Jyllands-Posten.

"Now, that's the new normal. Like we lost. Something that was OK is now not OK," Stone said.

Of course, for a long time, religious mockery on TV wasn't OK either, Bark observed. "Networks used to be loath to even touch religion," he said.

With rare exceptions ("The Simpsons" the most notable), until the mid-'90s, shows with religious themes -- such as "Highway to Heaven" or "Touched by an Angel" -- stressed earnestness and optimism.

But in the 500-channel universe, questioning religion, and all that comes with it, is now more acceptable, Bark said.

"Things are done now that weren't done then," he said.

If the satire is handled well, there's no reason for Mohammed to be untouchable either, Muslim writer Aziz Poonawalla said on his Beliefnet blog.

"I don't watch 'South Park,' and likely never will," he wrote. "But I much prefer their attempt at depiction of the Prophet SAW [May Allah's prayers and greetings be upon him], which is rooted in a simple need to assert their creative freedom, rather than any genuine intent to defame or insult Islam -- quite unlike the Danish newspaper cartoons, which were created with only malice in mind."

Bark remains surprised at the controversy the episode has stirred.

"Religion is touchy, but ... in this case, since they're lumping all religions [together] -- as usual -- and they've made fun of Jesus [and others], I'm surprised that anybody gets upset anymore over what they do," he said.

Certainly, Stone and Parker aren't going to suddenly change their attitudes. The pair recently announced a new musical based on the Book of Mormon, and they care too deeply about the "South Park" universe to go soft.

"You guys aren't afraid to pick at an old scab?" BoingBoing's Xeni Jardin asked.

"We're 200 shows now, so now what?" Parker responded.