Inspired in part by the ancient Chinese curse: May you live in a time of change.
The cognitive ability of former theists depends on at least two factors. One is how thoroughly they’d been indoctrinated; another is whether they have been, or now are, too burdened by responsibilities to examine their need for dogma.
Because the first of those two factors is all but self-evident, I will consider the second one first.
The body has an immune response. Unless it has been weakened, as is the case with HIV, it reacts in a series of ways to the presence of substances not recognized as a constituent of the body.
The mind has a similar “immune response”. The quickest response, if it hasn’t been damaged by religious indoctrination, might be the ability to recognize nonsense.
A specific instance, informed by my experience with Catholicism, may explain adequately. Kids in Catholic high schools, though indoctrinated in the lower grades, question what they are told and later might ignore the rules they’d been taught. A boy taken from school so he can support his parents, will have few opportunities to doubt and later might obey the rules. Observant Catholics who marry may burden themselves with more children than they can provide for, but the Catholic hierarchy don’t care; death remedies everything. That boy was my dad. I don't know how many thousands of dollars he had paid to send five kids to Catholic schools; before he died he knew we had all quit Catholicism and/or religion.
Go with that for now; I will add more later.
>Death remedies everything.
You nailed the promise of religion right there. As Neil Carter recently noted, we atheists believe in life before death. A radical bunch, aren't we!
So you're saying that being burdened by responsibility reduces the capacity to recognize nonsense and to question rules we've been indoctrinated with as children? Being burdened by responsibility seems to me to reduce the capacity for higher level thinking broadly. When we're operating at our stress limits we tend to rely on habitual coping behaviors.
This ties in with "Bending Truth", with religions and other groups exploiting cognitive dissonance. Often the mind's "adaptive" response in seeking consistency isn't so adaptive after all...
GC - you forgot to mention that they're exploiting cognitive dissonance they themselves have created.
A bit more: math, science, and dogmatism.
In two Catholic high schools I didn't understand 9th grade algebra, loved 10th grade plane geometry and reasoning my way through a proof, tolerated 11th grade chemistry and loved 12th grade physics, which showed me a use for algebra.
The US Navy took me to a war where I did electrical work on a destroyer, often off North Korea’s east coast as we shot up the coastal railroads. Out of the Navy and in college I studied electrical engineering, became an agnostic, earned a degree in math and economics, and did graduate work in physics and mathematics with computer applications.
Out of college, happily employed and well-paid, I realized that the math and physics courses I had taken and their requirement that I reason and have evidence, together with agnosticism, helped me repair the damage done during 12 years of Catholicism’s dogmatic demands that I believe and obey. I occasionally write short fiction (my own porn); when dealing with real stuff I want laboratory evidence and clear thinking, briefly stated. Math requires only deductive reasoning; physics requires both deductive and inductive reasoning.