They are too rational for religion but desperately need meaning (or whatever) so they convinced themselves they could literally talk directly to god (after he exists he will simulate their exact personalities at this exact moment in time).
They probably believe(d) they are/were but cults exploit a lot of fundamental human biases, desires and weaknesses. Pretty much anyone could fall in with a cult given the right approach. IMO all believing you're too smart for a cult gets you is a blind spot that lets the right cult sneak up on you even easier.
