July 2015 marks the fiftieth anniversary of the arrival of Jim Jones’s Peoples Temple to California, and in September, it will be half a century since the death of a nearly forgotten spiritual leader whom Jones admired and emulated: Father Divine, founder of the Peace Mission movement. Retracing a journey made by Jones and his followers, I recently traveled from California to Woodmont, a nineteenth-century French Gothic manor in Gladwyne, Pennsylvania, a wealthy suburb on Philadelphia’s Main Line. Woodmont is the last stronghold of the Peace Mission movement and the residence of its aged matriarch, Mother Divine. Despite Jones’s obsession with Father Divine, the connection between these two charismatic leaders was not well understood at the time of the Jonestown massacre, or even in the decades that followed. Recent studies authored by a pseudonymous researcher named E. Black and published on San Diego State University’s webpage “Alternative Considerations of Jonestown and Peoples Temple” have illuminated this compelling link—the potential wellspring of Jones’s messianic claims.

We’ve all heard the phrase about drinking the Kool-Aid, since that’s what finished off most of the settlers at the agricultural commune founded by Peoples Temple in Guyana. A cyanide-laced beverage—Flavor Aid, for the record—was consumed by more than nine hundred members of the Temple there in November 1978, killing them all within minutes. Now synecdoche for undergoing indoctrination by hypnotic forces, usually emanating from a cultish leader, “drinking the Kool-Aid” was a ritual of faith for members of the Peoples Temple. In the legendary “white nights” at Jonestown, colonists rehearsed this act of mass suicide in the months preceding their deaths. Simulated suicide was considered proof of their devotion to the revolutionary mission of the Peoples Temple. They’d already dedicated their lives to the Temple’s cause. But, Jones instructed, they must always be prepared to die for it.

Though obscure in popular memory, the “cause” advocated by the Peoples Temple was nothing less than total revolution: the Jonestown agricultural settlement was intended as a utopian social experiment in communism. Jones adapted the notion of “revolutionary suicide” from Huey Newton’s autobiographical account of the early days of the Black Panther Party and his personal crusade against American imperialism and racism. The young Reverend Jones may have started out preaching in the McCarthy-era Midwest, but he claimed to have held socialist and communist convictions ever since he was a child. He was a notorious liar, but if this was one of Jones’s overstatements, it was only a slight one: his wife, Marceline, recalled that her husband had privately expressed his admiration for Mao Zedong just after they were married, in 1949, when Jones was only eighteen years old.

Peoples Temple was nominally a church that originated with a...