What happens when you’re a time lord–a humanoid race that can, in simplest terms, manipulate time and acts–and you meet another being who claims to have existed before time even began? If you’re Doctor Who, the last of the time lords, it shakes your faith.

In the recent two part episode “The Impossible Planet”/”The Satan Pit,” (which aired on the Sci Fi channel) The Doctor and Rose, his travelling companion, come upon a space station of humans located on a small planetoid that is somehow able to resist being pulled in to a nearby black hole. The station’s crew have detected an unknown power source responsible for keeping the planetoid stable in the black hole’s orbit.

But then strange things start to happen: The Ood, a squid-faced clone race that serves the crew, tell Rose ominously that “The beast and his armies will rise from the pit and make war against God.” And crew members start hearing voices and experience demonic possession.

By the time we realize that the “beast” being talked out is the beast with a capital “B,” this episode starts to feel reminiscent of the plot of the computer game “Doom,” in which demons invade a space station full of scientists through accidentally-opened portals from hell. Like the videogame and spin-off movie, the episode touches on the inherent dangers in the never-ending quest for knowledge

The Doctor, hesitant to investigate the pit, says, “That is so human, where angels fear to tread. For once in my life, I’m going to say retreat.” In digging theologically deeper than the popular videogame, the audience sees something unusual: a doubting doctor.

Usually quite confident in his mastery of all things temporal, the Doctor is thrown for a loop when the Beast says that he has the existed and was trapped on the planetoid since before time. “What does that mean? What does ‘before time’ mean?” The Doctor asks incredulously.

“Before this universe was created,” the Beast replies.

“That’s impossible,” spits back the Doctor.

“Is that your religion?” asks the Beast.

“It’s a belief.”

The Doctor challenges the Beast by asking “which devil are you?” When The Beast starts pointing out the crew members’ darkest secrets, the Doctor retorts that a good psychologist can do that as well and points out that there are “representations of the horned beast right across the universe. It’s the same image over and over again. Maybe that’s what the devil is in the end, an idea.”

But we’re never quite sure if the Doctor believes his own rationalizations. When the Doctor finally comes upon the massive, manacled, horned beast, he admits, “I accept that you exist. I don’t have to accept what you are.” Ironically, for a character who clearly values science and reason over religion and myth, it’s his faith in his partner Rose that ends up saving the day. As regular viewers of the show know, there’s nothing shaky about that.