UPG, or Unverified Personal Gnosis, is a driving force for many modern Pagans. Working with incomplete systems, lost to history or accident, we turn directly to our deities for guidance. Of course, such guidance has to come through our religious experience one way or another, and may be distorted by our desires or previous experience (if you think it is genuinely coming from somewhere else at all!), and so in the first instance it is Unverifed.
(Pagans are not, of course, seeking the high levels of verification preferred by many scientists and philosophers; in this context, verified means something more like justified or supported.)
This would be a good point for a personal example, but I can’t think of one that’s really clear; much of my own UPG is small, or meshed with pieces of related lore, and I’d spend longer giving you the background than talking about UPG.
That points, I think, to one of the problems: UPG which gets published, which is not clearly marked as such. Of course, a community can choose, with whatever support it likes or none, to take on someone’s UPG as truth (indeed, many religious movements have started out that way). But we get into trouble when we can’t tell, for example, what is the UPG of a modern author, what is the UPG of an ancient author, and what was accepted by ancient communities as truth.