I wonder if part of this is a reaction to "scientific claims" about human nature. When you're told that you do X because of Y, or think Z because of T, you start to feel like a puppet. If your mind is just rationalizing what you've already chosen, you're kidding yourself, so how can you communicate with anyone else? Or can I even cogito?
If you try to shoehorn human experience and communication inside the universe bounded by sense perception and what can be tangibly measured, there's not much room for a "you," and still less for communion. In a way you "gain the whole world" in terms of what power the approach can give, but you lose your soul. That's not universally popular—even Faust regretted the bargain.
Of course you know better, but the these days default parameters of the debate are Descartes': even if you're not a puppet, you still wind up with an incommunicable reality.
There’s another way, of course—or two, or three. One way says that statements about our nature refer to things that "ought" or "ought not." "Ought" is not something you can derive from science, and if you propose to think only in categories of sense-perception and tangible measurements, you're cut off from that. You may find the oughts inconvenient sometimes (like me), but you are free to do the oughts or not. This leaves room for "you," for communion, and purpose—and a creator.
That last item can be frightening. Suppose my creator has different priorities and different ideas about my nature. Will conforming to my creator lose me myself?
Christianity says "just the opposite," but you can see how the prospect would look to someone who believes their nature is their perception of it, malleable by their choice.