To many, their faith based actions resulted in effects that are significant enough to them that it meets and exceeds any and all criteria of acceptance of that belief as valid.
I personally think it is fine to be curious and ask questions but it is absolutely foolish for a person to expect they can understand any and all things.
For most of your curiosity, it seems you are attempting to group people and say "these people believe for this reason",I think it's better to try and understand individuals instead of groups if you're curious about motives.
> ...significant portion of thoughtful religious aren't more or less of that variety and do believe they've joined a mostly or entirely correct religion, miracles and supernatural occurrences and all being actually true.
I can't speak for others but I am 100% sure of not only miracles of the past but also miracles that happen in this day and age.
As some say: "There is no argument that can overcome experience". That is to say, if I literally saw legs grow right before my eyes for an amputee as an example,you can't convince me it didn't happen without asking me to stop believing my own five senses which I rely on to percieve reality itself.
It's the ones who have wrestled with the stuff that I have trouble getting in the heads of. Do they all believe? Do even most of them? Surely not in the same way as those covered above—surely their faith is qualitatively different from that—but then, how? Or those who claim to be devout but hold serious secular power—are they really? Even most of them? And again, my trouble is with specific sets of stories and dogmas, not general "I like to think there's a higher power" stuff, which I have an easier time "getting", and in fact it's hard for me to understand that any significant portion of thoughtful religious aren't more or less of that variety and do believe they've joined a mostly or entirely correct religion, miracles and supernatural occurrences and all being actually true.
And that's before we throw in cultural and time gaps. What was the faith of the abbot or abbess of a 13th century monastic community like? What was it like in their heads? To what degree did a Pope, considering whether to grant one of these communities recognition, see their duty as political versus carrying out the will and protecting the interests of an almighty deity that became a person (only kind of, sort of, but not really—it's complicated, if you want to avoid heresy) then died, then some fly on the wall might have actually seen the dude's corpse re-animate—imagine the sight!—and some real, actual angels push a stone around, and all that really happened. That's where I get lost, trying to tease out motivations based on faith versus those where the faith's something else—social posturing, maybe.