WITCHHAMMER is a Czech horror film, based on the actual inquisition notes from the 17th Century, a time when superstition was rampant, The Church was ultra-powerful, and Christianity was seen as the only true religion.
When an old woman absconds with a single communion wafer, she is used as proof that The Devil is on the loose, creating his coven of witches. When the Inquisitor is brought in to investigate the situation, he soon finds just what he needs to get his convictions.
As others have pointed out, this movie is an excellent allegory for what was taking place in Czechoslovakia during the 1950s, under the boot of communism. Such "interrogations" were used, as in most cases, not to get to "the truth", but to break the will and destroy the mind.
One thing is made crystal clear in this film: If you hurt someone, anyone, enough, they will say whatever you want them to say, regardless of how absurd or untrue it may be. This has been common knowledge for thousands of years, and persists all over the world, even in this "enlightened" age.
WITCHHAMMER gets the point across like no other example of its subgenre: These women are in a no-win situation, and the men standing in judgement over them are sadists, interested only in confessions, no matter what agony must be inflicted to extract them. Anyone who seeks to help the condemned, no matter what position they hold, will face the same, grim fate.
A disturbing, brutal movie for its time, you won't soon forget it...