The Higher Source cult seems to have combined ancient Gnostic ideas about the soul belonging to a realm of light outside the earth with a sort of technological gnosticism associated with Artificial Intelligence research. This holds that the essence of the personality is information, which can be transferred to other media than flesh. This lies behind "life extension" technologies like freezing the heads of corpses so that they can be plugged into a new "motherboard" in the future.
This shows the extraordinary persistence of pre-Christian ideas into the modern world. The confusion is symptomatic of the way in which scientific ideas and technical knowledge, can be subsumed into pre-scientific myth. The idea of a higher plane is rooted in a cosmology where ideas like "higher" made sense as directions in space. We know now that they don't; but the urge to read human significance into the stars seems still irresistible.
There is an irony, too, in the fact that computer programmers should believe in souls as disembodied selves, which can somehow be beamed up to some watching spaceship. This is exactly the idea of a "ghost in the machine" which had seemed completely discredited among educated people. Indeed, the crisis of Christianity may well be connected with the fact that the idea of souls makes less and less sense.
A belief in resurrection on some spiritual or higher plane is something that almost all Western Christians have now abandoned. That is not to say that they don't believe in eternity: but they no longer see the afterlife as something to which they will be beamed up. The archetype remains powerful. It may have been conflated with a similar belief, popular among techie types, that a human being is really a sort of software running on optional hardware.
If human identity is at some level the product of a huge series of neural calculations and reactions which could in principle be described mathematically, then it is hard to see why this should not be written out in some enormous code string and blasted through the universe like a radio transmission. Quite how you would decode and play it back is an open question; but if you are clever enough to hide behind a comet and communicate only with the Earth's enlightened inhabitants, it should not be too tricky.
Ideas like this are reasonably common in the techie world. All it takes is one powerful and charismatic leader to distil them into a dangerous brew. The Higher Source group seems to have had such a leader in "Brother John".
Only a tiny proportion of cults with authoritarian founders end up committing suicide. The charismatic leader provides what is probably a necessary cause; so does social isolation, so that the common sense of the surrounding communities cannot provide a brake on the group's imaginations.
But there is almost always a final, precipitating cause which can be recognised without any theological training. In the case of Jonestown, it was the group's murder of an investigator which seemed to leave its leader with no choice. He decided that if he was going to go, he would take his followers with him. In the Solar temple suicides, there seems to have been financial pressure which made an option the group already thought reasonable seem inevitable. When more is known about the motives of the Higher Source group it will be surprising if they were purely theological.Reuse content