"Gnosis Terrorism" is a term that refers to the actions of a man named Grimoire Verum (along with several accomplices) who unleashed manipulated Gnosis to attack the capital cities of several planets a half a year before Xenosaga Episode III. Apparently, Grimoire and those who followed him all died in the U.M.N., with no real explanation as to how or why he was controlling the Gnosis. It seems that Shion and Jin were also involved in the incident, and though it was never mentioned to what extent they were involved, it was enough for the KOS-MOS Project to be halted and Shion's voluntary resignation from Vector Industries.