The events at Jonestown in 1978 seared into our collective awareness the potential threat of religious organizations. Part of what was so terrifying was that relatively few people thought the group was dangerous up until the day the world learned that over 900 people committed suicide or were murdered within the religious commune known as Jonestown.
Those who died did not fit our expectations of religious fanatics. They were members of the Peoples Temple, a group dedicated to caring for the poor and embracing the disenfranchised. They weren't screaming on street corners for people to repent or burn. most radical public facet was their interest in communism. Their leader, Jim Jones, was a member of the Communist party and used his pulpit to spread the value of communism to others.
Unfortunately, Jones bore many of the common marks of a cult leader, insisting on growing control over the lives of his followers, and comparing himself with religious figures such as Jesus, even performing faith healing to win over his flock. As his control began to slip, he commanded his followers to partake in '"revolutionary suicide," an act that many seem to have willing done.