Creationist Ken Ham’s strange comment about aliens rendered the usually loquacious Neil deGrasse Tyson almost speechless during his recent appearance on “Real Time with Bill Maher.”

Ham, the president and CEO of Answers in Genesis and the Creation Museum in Petersburg, Ky., said in a July 20 blog post that humans should stop searching for extraterrestrial life because aliens likely don’t exist. Even if aliens do exist, he added, they would almost certainly go to Hell.

“I do believe there can’t be other intelligent beings in outer space because of the meaning of the gospel,” Ham wrote. “You see, the Bible makes it clear that Adam’s sin affected the whole universe. This means that any aliens would also be affected by Adam’s sin, but because they are not Adam’s descendants, they can’t have salvation.”

During the show, which aired Friday, Maher asked Tyson what he thought about Ham’s comment. In response, Tyson uttered just three short words before pursing his lips and going silent: “That’s messed up.”

During a panel discussion earlier this month, NASA experts said it was “highly improbable” that humans are alone in the universe, adding that they expect to find evidence of extraterrestrial life before too long.

“I think in the next 20 years we will find out we are not alone in the universe,” NASA astronomer Kevin Hand said during the discussion.

In his 2007 book Death By Black Hole, Tyson wrote that it would be “inexcusably bigheaded“ of humans to assume that Earth is the only place in the universe with life on it.

He’s also said that aliens may already know we exist and have decided we’re too dumb to bother contacting.

“I wonder if, in fact, we have been observed by aliens and upon close examination of human conduct and human behavior they have concluded that there is no sign of intelligent life on Earth,” Tyson said in an interview with Business Insider last year.

Ouch.