The ISIS terrorist who slit a priest’s throat and used a nun as a human shield during an attack in France on Tuesday bragged about his intended assault to an audience of up to 200 people on an encrypted communications app nearly a week before the spree.

The audio files recorded by Adel Kermiche for a private group on the Telegram app were obtained by L’Express magazine and verified for the publication by a source close to the investigation.

Kermiche, 19, says he will “enter a church, take a knife and make a carnage,” according to a translation of one chilling message.

The messages were found during the subsequent investigation into Kermiche, the source told L’Express. Kermiche and his partner, Abdel Malik, were killed by police as they exited the Normandy-area church, attempting to use nuns to shield themselves from bullets.

A short time earlier, they had entered the church, forced an 85-year-old priest to kneel and then filmed themselves slitting his throat. Another churchgoer was severely injured during the attack.

In one message, Kermiche, who attempted twice to travel to Syria to join ISIS, tells the other group members that it’s easier to carry out a terror operation in your home country.

“You slice two or three heads, and it’s good, it’s over,” he says.

Kermiche says he was inspired by a “spiritual guide,” a sheikh, or religious leader, he met while in prison in Fleury-Merogis. Kermiche was serving time for one of his unauthorized border crossings to try and join ISIS.

“In prison with my sheikh,” Kermiche says. “He gave me ideas.”

Kermiche also says he decided to act to prove his mettle to “other brothers” who made fun of his “commitment from a sofa.”

The day before the attack, Kermiche assures his followers that “big stuff” is ahead.

“I warn you in advance, three, four minutes, and when the thing comes, it will share the line,” he says, referencing “a picture or video.”

Kermiche says those who share the images “will be rewarded.”

Just an hour before he entered the church, Kermiche reminded the group to “share what follows,” but he did not post again.