Is atheism self-contradictory ?

[Astonished]

I don't know, a mind capable of accurately representing the environment and it's relationship to that environment probably has a strong selective pressure in it's favor.  Is that not, itself, an example of ascertaining truth?

/facepalm...

Did you not read my entire post? Did you not comprehend it?

Here is a snippet from my post:

"A brain that is tuned for ascertaining truths and falsehoods doesn't necessarily follow from this process. For instance, a mutation could be introduced that negatively affects the cognitive faculties but nevertheless dramatically increases the survivability of the species through a different means. This would then be passed down to later generations. Or a mutation could be introduced that produces a false belief, but the false belief increases survivability. Finally, it may be that our brains are very good at things like "stay away from spiders" or "don't jump off cliffs" but they aren't good at abstract concepts like mathematics and philosophy. For example, maybe there was a mutation that increased our chances of understanding Calculus or Quantum Mechanics, but since being good at Calculus or Quantum Mechanics doesn’t increase your chances of surviving millions of years ago, it was left behind for simpler things like “don’t stay under water for too long.”

Notice how I provided an example of how evolution could be good at certain things but bad at others. The point is evolution doesn't necessarily produce a reliable brain for ascertaining truths. The fact that evolution lead to the production of a brain that is predisposed to the belief "fire hurts and destroys" doesn't mean that evolution lead to a brain that produces or is predisposed to only or mostly true beliefs. You've effectively ignored the meat of my post--which seems to be a trend on this forum.

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Well, first of all, we’re talking about brains, not minds.
Secondly, yes, a brain would be required in that instance—or something akin to a brain. Instinctive reactions are from the brainstem, which is part of the brain. The brainstem was produced by evolution.
And you’ve effectively missed the meat of my post.

And a brain that is tuned for ascertaining truths also don't necessarily NOT follow from this process. The two aren't mutually exclusive anyway, we still have both now even if one of them isn't useful nearly every day if we're cognizant of how to minimize risk. Not every square inch of nature is a constant flow of fight-or-flight situations, nor was it even early in our evolution; cave paintings and the like suggest that some of these early intellectuals survived long enough to do that even though it didn't really offer any evolutionary advantage to their survival. Without ascertaining truths we would never have figured out how to bang the rocks together, we would have probably been too piss-scared of the noise to try it more than once. Sure, the discovery was probably by accident but we inevitably did figure out how to put two and two together to keep making fire and cooking our food and likely rendering our appendix obsolete without even realizing it. What dominates our cognition, the instinctive responses to various stimuli, or whatever other intellectual or recreational endeavors we care to spend time doing? There's no reason evolution couldn't have favored both, or favored more superstitious behavior in some humans in one part of the world and more rational thinking in humans in other parts of the world. Obviously there would then be overlap at some point when these different cultures meet, or situations in each culture where they'd still have to rely on the other behavior at times.

You also seem to be equating mutations about how the brain works with pure biology; you probably meant that these are memes, and memes don't generally mutate like that or they die out because once a meme changes, it becomes unrecognizable in any previous form and leaves no vestiges to examine, unlike actual DNA and examples of animals (including humans) with vestigial features of our past. Memes that are verifiably useful (cooking food, using tools, etc.) will endure with little to no alteration because they work and stand the test of time. The meme of appeasing the sky gods when you ask for rain seems to be the exception to that, since it was never able to work reliably, and a good reason that sort of thing (as a broad reference to all religious belief and behavior) is that there were still no forthcoming answers about what was out there, why they didn't get results even if they were sacrificing their virgin daughters, and of course very effectively murdering anyone with a dissenting opinion. So religion seems uniquely to be the one meme that endures for bad reasons and is passed on by extremely unnatural selection. If you think about it, in terms of memes, religion is one of the earliest forms of eugenics.

Now, if I understood you correctly (and I never make that assumption around here; frankly I never make the assumption anyone even knows what they themselves are talking about) you seem to want to imply that a brain that formed via evolution over millions of years, which is prone to this or that problem, is an unreliable means of ascertaining any real 'truth' and I believe I disproved that when I countered someone's primitive interpretation of the presuppositionalist argument. But what I will say is that your defense of there needing to be something functioning as a brain in order for us to have even the most basic instinctive functions doesn't exactly hurt the idea of the brain being a good means of learning and knowing things; as the brain grows in power and complexity, its cognitive capability is vastly increased. We have the largest brain-to-body-size ratio of any other animal and it shows. There are some animals with sophisticated communication capability and we've even taught gorillas some sign language in one or two cases I'm aware of. If you want to argue that our brains, earlier in our evolutionary ancestry, were unreliable, then sure, I'm more than happy to agree to that. But evolution is a constant process and at a certain point, we stopped needing to constantly rely on the 'false belief' instinct, and that's been the case ever since. Yes, we will jump and shriek when we see something that looks like a snake or other predator is jumping out at us, that's just programmed in. But as I stated before, that is not the dominant focus of our cognition on a daily basis. As for why we developed a capability for mathematics, or hell, even spoken language, natural selection is pretty much the key there; you don't choose what form mutations take on, the DNA will recombine in whatever way it will and whatever emergent properties that result are what they are. If those advanced ideas (even before figuring out how to actually put them into practice) didn't help us survive in the wild, they also sure as hell didn't become a detriment to us surviving either, did they?

I'm still not sure exactly what if any point you were trying to make but I think I pretty well covered everything in the stuff I quoted. I highly recommend reading The God Delusion, it was actually what helped me understand a lot of this and put it into words that I assume are at least mostly understandable.