Regardless of that, why is it, then, that those who are theists have their sensus divinitatus working well enough to be able to sense God, while others do not?
First, a qualification. On a Christian understanding, the precise problem caused by the fall is both noetic (belief-related) and affective (attitude-related). In large part, our
sensus divinitatus can give us right truths about God but our attitude prevents us from welcoming those truths; so we literally lie to ourselves. It's also worth pointing out that this is a very large-scale description of the problem. That is, it's a description of the problem for humanity
writ large, not for any particular human being.
To your question, then. On a Christian analysis, God reveals himself to certain people through revelation, a revelation that effects a repair of the
sensus divinitatus (to the extent that it was the specific problem). Thus the person can perceive God. God also repairs the affective capacity of the person such that the person welcomes that perception. Thus the person perceives God and welcomes God. All this is pretty well laid out in the first three chapters of the book of Romans. Go there for a more detailed exposition. Just keep in mind that, once again, we are dealing with a very large-scale description of the situation.
My point, once again, is that Christianity is comfortable with the notion that science may have discovered that we are hard-wired for religious belief yet not everyone has a religious belief. Indeed, on a Christian understanding of things, that's just what we'd expect.
Do you think that atheists all deny God's existence, even when it is revealed? God has not revealed himself to those that are atheists? Or is it something else?
There is a sense in which God has revealed himself to everyone. Theologians call this "general revelation." As the aforementioned passage in Romans says, everyone is well enough informed about God to be held accountable for concealing or obfuscating God through unrighteousness.
There are some (very few) for whom general revelation is enough because they are not ideologically, culturally, or attitudinally resistant to God. So when they turn their attention to general revelation, they perceive that God is responsible for creation and conscience, and this in turn spurs them on to cultivate a relationship with their creator. But that won't do for most because, as I've said, there's more to it than mere damaged equipment. Even when the equipment works properly, some people simply resist. It's like a delusional person who, shown that he's delusional, prefers the delusion. Thus he comes up with all sorts of rationalizations for the delusion.
Regrettably, I'm afraid that your other questions take this thread much too far afield, so I'll just leave them unanswered in this thread. If you want to start another thread based on them, I could provide my two cents' worth there.