Good post. I wanted to mention the so-called coherence theory of truth by name here, which I believe you have just described, and probably already know by that name. Internally consistent mathematical systems generate a priori truths (not derived empirically). This is a different definition of truth. From
The Coherence Theory of Truth (Stanford Encyclopedia of Philosophy)
"A coherence theory of truth states that the truth of any (true) proposition consists in its coherence with some specified set of propositions. The coherence theory differs from its principal competitor, the correspondence theory of truth, in two essential respects. The competing theories give conflicting accounts of the relation that propositions bear to their truth conditions. [snip] According to one, the relation is coherence, according to the other, it is correspondence. The two theories also give conflicting accounts of truth conditions. According to the coherence theory, the truth conditions of propositions consist in other propositions. The correspondence theory, in contrast, states that the truth conditions of propositions are not (in general) propositions, but rather objective features of the world."
But that's not religion. If it's true, it's history. Religion's truths would have to be truths determined through faith, and nothing believed by faith can be called truth by the correspondence theory of truth (or the coherence theory).
You must be employing a third definition of truth here, one that considers undemonstrable intuitions truth. The empiricist doesn't count such ideas as truth, since they can't be used to describe or anticipate nature. Furthermore, whenever I've asked what some of these spiritual truths gleaned by this other way of knowing are, I get no answers unless they are other vague, undemonstrable intuitions.
None available to man.
No religion has made me stronger, at least not directly in the way you probably mean. The only one I participated in taught me that faith and religion are not the path to truth, and can even cause one to make significant errors in life if religious doctrines that might affect life choices are acted on.
Your graphic doesn't support that. It didn't mention atheism.
Even so, the rise and fall of atheism and religion are going to be tied to the quality of life. Where life leaves people feeling vulnerable, they will be more religious. People become more religious as they lose control over their lives. In places in the world where this is happening, where people feel most vulnerable, they pray the most. As their worlds become more threatening due to climate change and the extreme weather, drought, and famine that follows, they will pray more.
This is the reason that religion plays much less of a role in the lives of those benefitting from the advances of humanism, especially science, which has made life longer, more functional (think eyeglasses), safer, easier (machines), more comfortable (air conditioning), and with the rise of the modern liberal secular state with guaranteed personal freedoms transforming people from serfs and subjects to autonomous citizens.
Religion does nothing like that for people, and people who have that want less religion. There's a reason it's easier to convert people on Skid Row and Death Row, where people have lost control over their now miserable lives, than on Restaurant Row, where they feel safe and comfortable. That kind of rise in theism doesn't speak to its truth value, but rather, its comforting value in troubling times.
Somebody already corrected you about it being fewer, so I'll amplify on that. At the risk of seeming pretentious or pedantic, here's why: In English grammar, some nouns are called countable, like table(s) and chair(s), and others not, like furniture. You can have one or three chairs, but not one or three "furnitures." So, one can have fewer chairs and less furniture, but not vice versa:
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