Apparitions from heaven???

[GrandizerII]

Well apparently those people who didn't see anything weren't devout enough.

I don't think so. 

Most people there, numbered in the tens of thousands, saw the zig zagging sun movements across the sky. But some didn't. Plenty of the ones who didn't were Catholic (as has been linked here already), and plenty of the ones who did were skeptic. 

That's the thing with miracles. We don't understand why God grants this gift to some but not to others.

Even if they were "skeptic", that doesn't make them immune to cognitive delusions. It's not always about whether you believe at first or not. It's more about how you are cognitively conditioned/wired.