The work covers hagiographic motifs which recount the “spiritual warfare” experienced by the founders of monasteries in the 14th–15th centuries. The spiritual struggle was waged in the period between the settlement of a hermit in a chosen wilderness desert place and the creation of a monastery. It was at this time that the site of the future monastery underwent the process of sacralization, i.e., the transformation of an unclean, “alien” place into a holy one. A large number of the lives of saints, reporting the practice of the sacralization of space, include episodes of the fight against demons. The analysis of these hagiographic motifs suggests that, in the view of many hagiographers, the theme of resisting demons was an integral part of a clearly defined and simultaneously original system of describing the spiritual assimilation of the site where the monastery was to appear. According to the hagiographers, the saints retired to remote, deserted places, inhabited by demons. The beginning of the sacralization of these places (the erection of the cross, the chapel, the exploits of prayer and abstinence) is perceived in the lives of saints as a strong blow to the demons. In their turn, the demons tried to frighten the hermits and drive them away from their chosen place in the most cunning ways. To enhance the realism of demonic delusions, hagiographers described their appearance in human or bestial form. Some texts reported how the devil sent robbers, pagans or local residents in order to harm or even kill the saints. These descriptions represent a separate kind of “spiritual warfare” motif, in which fear of spiritual danger is complemented by threats of physical assault. In each case, the hermit had to resist the attacks and stay in the chosen place until the complete victory over the demons. Corresponding hagiographic episodes are accompanied with a description of the practices adopted by hermits to struggle with delusions. According to hagiographers, the monks used such remedies as the Jesus Prayer and the sign of the cross, as well as prayers built from psalm verses and New Testament quotations. According to the vitae, the appearance of a monastery on the site of the deeds of the monk became possible only aft er his victory over demons, which often marked the transition to the final stage of the process of sacralization of space.