Do you think possibly that Jul will be revealed to his followers as a ‘non believer’ in the Forerunners? And if so, what do you think will happen to him?
He’d still be the Didact’s Hand, and I doubt the Didact would care whether or not Jul was as stupidly fanatic in worshiping the ground he tread upon as the rest of the bunch. In fact, that may be why he is the Hand.
In the extremely unlikely case that somehow Jul was to revealed a non-believer by some all-knowing source that the Covenant honestly believed (they’d obviously call out that as blasphemy, accusing the Hand), then so what? He’s still the Didact’s lieutenant and has the support of Promethean units.