Monasteries, churches and granges defended against raids. Monastic communities were, mainly, made up of high status people. Monasteries were also often used as stop over residencies for lords. Much monastic 'fortification' such as gatehouses are actually status displays rather than really defensive, although military raids and peasant riots did occasionally put such defences to the test. Granges could hold considerable wealth so defences here were generally practical but also reflect the status of the parent community. Churches were an important resource for the local peasant community having many functions beyond spiritual succour; in unsafe areas like the Marches, this included short-term defence against raiding bands.
It is and was commonplace for churches to have towers and to be crenellated. The symbol of secular lordship, the crenellated tower, derived from the responsibilities of secular lordship to defend the community were thus appropriated to symbolise spiritual dominion. It should also be noted that belfry towers have particular structural issues to deal with heavy moving and vibrating bells and need to be substancial, thick walled and have small windows for these reasons, particularly in areas where the quality of stone and mortar was poor.
Bishop's castles and priest's towers are considered as private residences and are listed with other castles etc.