"At the risk of beating the proverbial dead horse, I wonder how a-theists explain the numerous (in my circle of acquaintances, nearly all) adults come to the conclusion of the truth of Scripture after being either a-theists or agnostics for many years? I've friends that are highly educated (as well as most who are divided among the less educated) who unabashedly declare their belief… can't all of them been brainwashed, could they?"
Well I would question that description of the world, to start with.In your circle of acquaintances ( how many acquaintances does your average human adult have? less than 10? 50? 100?, more?), nearly all adults you know have converted to scripture?
I am sceptical of that situation, for starters. How many? How long have you known them for? How did you know they were atheist or agnostic before they converted? Not buying it Clanad.
But, quite apart from that - people can and do as adults convince themselves of anything and go on to believe it quite sincerely - just think of the numerous proponents of various conspiracy theories, for instance. I could imagine some adults convincing themselves that religion holds the answer to lifes mysteries for them - and I do not have a problem with that.
If an adult wishes to follow a religion, having made up their own mind - fine and dandy, providing they then do not start whining that they are unable to accept gay marriage because it contradicts their religion, or that they should be allowed to have statues placed on government property but other cults cannot, or that their should be public prayer before a public meeting etc. In other words, that their religious rights and beliefs do not take precedence over human rights or national secular values.
But the critical thing, how we know that religiosity is largely an imprinted, learned thing, is the simple statistic that the vast majority of children of practising christians grow up christian (not muslim,or buddhist, or atheist); the vast majority of children of practising muslims grow up muslim - not RC, not Protestant, not Jainism or whatever.
And we know that much of that religious belief is therefore imprinted upon people at an early age, and that such learning tends to stick through to adulthood.This is self-evident and uncontroversial - It is a maxim attributed to Jesuits after all, that "Give me the child till the age of seven
and I will show you the man."
So for me, I would far rather that religion played no part at all in formal education until kids are able to make considered opinions of their own - say 16 or so.