[BluffTHIS!]

Gnosticism as usually understood was an heretical take on christianity, and there is no connection between that and that cult. But gnosis in general can mean any system based on secret knowledge, even a takeoff of an already existing religion. So just define gnosis as such and then show how that cult was based on what secret knowledge and how one could acquire same (join the cult).

Of course you should also try to gather empirical data such as showing the comet's trajectory was off predicted values due to the presence of a spaceship hiding behind and matching speed with it.