This is not a useful definition of a cult, though it is a short one. The primary characteristic of a cult is that adherents find it difficult to leave, not bec

This is not a useful definition of a cult, though it is a short one. The primary characteristic of a cult is that adherents find it difficult to leave, not because of the specific beliefs of the religion (e.g. Islam) but because of the mechanism of control. "Unconventional manner" doesn't really cut it. The key definition of a contemporary cult from the perspective of someone who has seen people join one is that the cult turns people inward to the cult and encourages them to cut off not just friends who question their belief but ultimately all non-cult friends and family. In fact you could argue that the primary quality of a mainstream religion is that it points itself outwards towards non-believers and does not condition receiving its care on belief itself. For example, the Unification Church is on a slow trajectory towards mainstream religion. The University Bible Fellowship, absolutely a cult and quite a scary one, is not on that trajectory.