The Church/La Chiesa (1989)

A church is built during medieval times on top of a pile of dead bodies that were considered possessed. Hundreds of years later a young librarian unleashes the evil within by removing a rock in the catacombs, and many strange events occur, and many people seem to have changed suddenly. Father Gus, the only one not possessed, must save the city from the pandemonium by finding the ancient secret of the church so it can crumble to pieces.

IMDb: https://www.imdb.com/title/tt0094860