Pelagius prophesied a great burning which would cauterize the universe.
His cult was an enemy of the Confederacy, and they tried to terminate his movement. The ghost they sent terminated many cultists, evading Pelagius' plans to trap him. Eventually Pelagius built a device which helped the cult capture the ghost. Inspired by the ghost's neural inhibitor, he created an "unbreakable mechanical faith," essentially implanting people with the technology to force them to share his beliefs (naturally, he himself had no need to be implanted). His cult became more adept at hiding themselves from others.
In 2502, years after the Fall of Tarsonis and the destruction of the Confederacy, a team of Kel-Morian Combine scavengers came to his planet. He sent his ghost to terminate two of them and capture the other two, who were noncombatants. Both were converted into members of his cult.