Flavia, the Heretic (1974)

Flavia, the Heretic (1974) Italy 1600: A convent of nuns are invaded by the Tarantula Sect on their annual pilgrimage. The cultists defile the place of worship, orgying in the chapel and desecrating the altar. One nun decides she can't take the religious oppression any longer and flees the convent upset that all the leaders are male.