Adulthood doesn't bestow on you amazing mental abilities to discern truth from lies
Well that's not quite it--it's the distinction between reality and illusion. And actually, adulthood DOES bestow upon you amazing mental abilities to discern reality from illusion. That's part of cognitive development.
I think Faith is right in making a fundamental distinction between children and adults, especially when it comes to the distinction between what is reality and what is not. Children are notoriously bad at this discernment.
The fact that children believe in Santa Claus does not equate to adults believing in demons. Children have imaginary friends and engage in "pretend play" routinely. If adults engage in the same behavior, it is seen as "abnormal" and a problem.
So overall, I think Faith has a point. The testimony of many people is evidence. As scientists, that evidence can't just be hand-waved away. It has to be explained rigorously, and while we certainly have lots of ideas and evidence that the underlying cause of these experiences is non-mystical, we can't demonstrate it rigorously enough to "answer" the evidence in question.