Houston televangelist Joel Osteen took a break from the stream of affirmations he posts on Twitter to share a photo of his son's college graduation Saturday.

"We had a great day celebrating @JonathanOsteen's graduation from the University of Texas at Austin!" he wrote. "So proud of him!"

The photo showed father and son doing the "Hook'em horns" sign, which the university calls "one of the world's most recognizable hand signals."

It is recognizable to many people, indeed, and some of them think of it as the devil's sign.

Twitter users began demanding explanations from Osteen, who preaches to more than 40,000 weekly at Lakewood Church. His televised sermons reach more than 100 countries.

Why on Earth would you use the devil sign? My goodness a thumbs up would work or you don't have thumbs??😶😶😶 — askofu indimuli (@ian_indimuli) May 20, 2017

That Demonic signal .... Pastor?! Really? — Jesse Samson (@JesseSamson4) May 20, 2017

The pastor's wife, Victoria Osteen, also took a picture with her son in "Hook'em" pose. And she, too, was assailed on Twitter for her hand gesture.

"Why you are showing illuminati symbol," someone wrote.

Another Twitter user piled on the confusion: "That sign is it not illuminaty??"

Congratulations @JonathanOsteen on your graduation from the University of Texas at Austin! I couldn’t be more proud! pic.twitter.com/cw7hcChut6 — Victoria Osteen (@VictoriaOsteen) May 20, 2017

That sign is it not illuminaty?? — shadrack wambo (@shadrackwambo) May 20, 2017

Why no, it is not the sign of a super-secret society. And if it were, we probably wouldn't know about it because, you know, it's a secret.

Really?!?! All university's have hand gestures. We have 🤘Hook em Horns. — Joy Bane (@Joytx66Joy) May 23, 2017

The Osteens are participating in a UT tradition that dates back to 1955, when a student noticed that the sign produced a shadow figure that resembled a longhorn, the university mascot. A male cheerleader introduced the sign during a rally before a big game against Texas Christian University.

Harley Clark, the cheerleader who would later become a judge, recounted that the dean of student life was upset and asked Clark whether he was aware of what that sign might mean in other parts of the world, like Sicily.

"Dean, you need to look on the bright side of things," Clark remembered saying. "Instead of our mascot being a longhorn, it could've been a unicorn."

To be fair, the "horn sign" has different connotations depending on where you are. In Italy and other European countries, the so-called devil's horns are a superstitious gesture meant to ward off evil.

Many also know it as a symbol of heavy metal. The gesture became associated with the musical genre around the 1970s.

So, congratulations on graduating college, Jonathan Osteen. Rock on.