If “A Quiet Place” — the screenplay that put writers Scott Beck and Bryan Woods on the map — was a rather tight-lipped, high-concept monster movie where the characters could rarely speak, “Heretic,” their latest film, which they wrote and directed, is the opposite. This is a talky chamber piece of philosophical face-offs, debate duels and wordy warfare, though the outcomes remain just as harrowing.

But the danger of “Heretic” is not anything extraterrestrial — an alien from another planet — but rather the most common, and mundane, of earthly predators: a man.

And what a man Beck and Woods have cast in their religious horror flick, effectively weaponizing the befuddled British charm of one Mr. Hugh Grant, who has fumbled and grinned through such rom-com classics as “Notting Hill,” “Bridget Jones’s Diary” and many, many more. The genius of his performance in “Heretic” is that his manner is no different in this horror film than those romantic comedies, it’s just the nature of the conversation — and what he’d like to do with women — that’s different.

The story starts with two young Mormon women on a mission to baptize converts. Sister Barnes (Sophie Thatcher), savvy, street smart and clad in black, is visually opposed to the bubbly, outgoing Sister Paxton (Chloe East) in her demure pink cardigan. The pair arrive on the remote Colorado doorstep of a Mr. Reed (Grant) on a rainy afternoon because he’s expressed interest in the Church of Jesus Christ of Latter-day Saints, and despite doing everything right, keeping their wits about them, they still end up in peril.

They enter this curious and claustrophobic home only when Mr. Reed promises his wife is baking a pie in the other room, but he draws them into his labyrinth using false promises and rhetorical exercises. At first, the girls are only in danger of being forced to listen to one man’s extremely pretentious opinions about religion, philosophy, culture, and yes, pop music, which is terrifying in itself. For some women, anything that comes after such a torture would pale in comparison. But because this is a horror movie, there are, of course, more immediate existential threats lurking behind doors one and two. The funny thing is that the designs Mr. Reed has in mind for these ladies are as derivative and unoriginal as his monologues, and that’s kind of the point.

As his questioning crosses taboos and boundaries, raising Sister Barnes’ hackles, cinematographer Chung-hoon Chung’s camera, which has been cutting between various degrees of close-up as the conversation progresses, breaks free from stasis. The camera floats around the room like an invisible spider, circling and circling, weaving this trio into a diabolical web.

What’s scary is not what Reed has in store for them, but how these young women already know how to placate and navigate a Bad Man, how to “politely wrap this up.” He’s nothing new, just more noxious. Despite his belief that what he’s imparting is radical or even insightful, his claims are banal, his methods rudimentary, even the revelations about his intentions all too predictable. Beck and Woods don’t have to dream up something alien when these kinds of garden-variety predators are all too insidious.

Furthermore, though Mr. Reed presents himself as an intellectually superior theologian, gilding his carefully choreographed arguments with props and theatrical flourishes, the script itself doesn’t hold him in the same regard. It never condescends to Sisters Barnes and Paxton, and the girls always have sound rebuttals at the ready; they are also observant, smart and canny. They’ll need to outwit him, first and foremost, and they prove that they can.

“Heretic” excels on the strength of its performances: Grant’s charm offensive, Thatcher’s wary knowingness, and East’s ability to couch Sister Paxton’s surprising strengths under her girlish mannerisms (this character is a more complicated iteration of her fervent Jesus freak in “The Fabelmans”). For Mr. Reed to meet his match in these people-pleasing Mormon girls, victims he sought out to manipulate, coerce and dominate — well, there is a gratification in that.

But because it is a genre flick too, there are overwrought visual metaphors, implausible twists and an unfortunate reliance on coincidence. The mechanics of the plot itself don’t quite hold up under scrutiny, which is a shame when the dialogue, performances and filmmaking craft are so tightly woven, moving in perfect sync. The tension and characters do allow us to skim over the flaws and foibles in the script, especially when the resolution is so hard-fought.

“Heretic,” as a lecture on faith and ethics gone awry, is a story of belief versus disbelief. If there’s anything we take away from this tale, it’s not that faith is bad, or good, but that it exists in the eye of the beholder. The only thing worth believing in is yourself.