According to the doctrine of the Fujufuse School, as 'naishin' were distinguished from believers of fujufuse and were not allowed to donate offerings directly to 'hocchu,' these 'donors' played the role of mediating between them.
そして不受不施派では教義上「内信」は不受不施の信者とは一線を画され直接「法中」に供養することが出来ず、「施主」がその間を仲介するという役割を果たした。