The TV personality made an appearance on The Late Show with Stephen Colbert on Monday, and shared—in great detail and with much passion—his belief that COVID-19 originated from within the walls of the Wuhan Institute of Virology.

Stewart said during his chat with host Stephen Colbert: “I think we owe a great debt of gratitude to science. Science has, in many ways, helped ease the suffering of this pandemic—which was more than likely caused by science.”

However, following his impassioned speech, in which he insisted that his rant was “not a conspiracy,” viewers were left not knowing how to take his words.

Taking to Twitter, @JustALilLost wrote: “I honestly can’t tell if @jonstewart is doing a bit or not while he goes on a conspiracy-filled rant about Wuhan and the coronavirus… like wow, way to throw more gas on the fire on the anti-Asian hate.”

@RazKoller tweeted: “Honestly can’t tell if Jon Stewart was joking or had a senior moment on Colbert. Take what he said, put it in the mouth of a Fox News presenter and it won’t feel out of place. And Colbert would have had a bit about it in his monologue the next evening…”

Echoing the confusion, @vodkasnowflake enquired: “is Jon Stewart joking or serious about the COVID lab theory.”

Following the interview, @Justsomedust tweeted: “Jon Stewart is flying real close to Qanon territory on Colbert. Expecting him to go anti-vax any moment now.”

“Wow, didn’t expect a @jonstewart borderline meltdown and dangerously misinformed attack on science on @StephenAtHome tonight,” said @motobeej. “I guess we are back???”

“Seeing Jon Stewart peddle the ‘Covid came from a lab’ theory as obvious fact on Colbert tonight is not something I was expecting,” wrote @robertbtaylor."

However, @cynicalboomer1 insisted that Stewart was joking, explaining: “All these people freaking out at Jon Stewart need to wake the f*** up.

“1. He is clearly joking (and definitely knows that nothing is yet proven). 2. The Lab leak is TOTALLY plausible. 3. Admitting #2 is NOT anti-chinese (although racists will use it so we need to be careful).”

Expressing a similar stance, @dannagal said: “Lots of folks will be uncomfortable w Stewart’s bit on Colbert. And yeah, I don’t love the ‘science needs to know where to stop’ line, but folks THIS IS WHAT SATIRE IS SUPPOSED TO DO.”

During his interview on Monday, Stewart said: “Novel respiratory coronavirus overtaking Wuhan, China. What do we do? Oh, you know who we could ask? The Wuhan Novel Respiratory Coronavirus Lab.”

“The disease is the same name as the lab,” he went on. “That’s just a little too weird, don’t you think? And then you have some scientists who are like, ‘So wait a minute, you work at the Wuhan Respiratory Coronavirus Lab. How did this happen?’ And they’re like, ‘Mmmm, a pangolin kissed a turtle?’

“No! Look at the name! Show me your business card! ‘Oh, I work at the Coronavirus Lab in Wuhan. Oh, because there’s a coronavirus loose in Wuhan. How did that happen?’ ‘Maybe a bat flew into the cloaca of a turkey and then it sneezed into my chili and now we all have coronavirus.’ Like, come on!”

Countering Stewart’s theory, Colbert said: “It could be possible that they have the lab in Wuhan to study the novel coronavirus diseases because in Wuhan there are a lot of coronavirus diseases because of the bat population there.”

“I understand,” responded Stewart, before continuing: “It’s the local specialty. And it’s the only place to find bats. You won’t find bats anywhere else!

“Oh wait—Austin, Texas has thousands of them that fly out of a cave every night—every night at dusk! Is there an Austin coronavirus? No, there doesn’t seem to be an Austin coronavirus! The only coronavirus we have is in Wuhan…”

“This is not a conspiracy!” Stewart went on to insist. “But this is the problem with science. Science is incredible, but they don’t know when to stop and no one in the room with those cats ever goes, ‘I don’t know if we should do that.’ They’re like, ‘curiosity killed the cat, so let’s kill 10,000 cats to find out why.’”

Monday’s instalment of The Late Show with Stephen Colbert marked the first time the show had a live studio audience since the COVID-19 pandemic upended production back in March 2020.

In May, President Joe Biden ordered intelligence services to carry out an investigation into the origins of COVID-19—which would include a probe into whether the novel coronavirus leaked from the Wuhan Institute of Virology.

Chinese government officials responded to news of the investigation by expressing frustration at the “political forces… fixated on political manipulation and blame game.”

Newsweek has contacted a representative for Jon Stewart and the Embassy of China in Washington, D.C. for comment.