I have long had a facination with Mystical Theology, which is also know as Apophatic Theology or Negative Theology. If you share these interests in any way, one book I have found quite accessible as an evangelical Christian is "The Mystery of God: Theology for Knowing the Unknowable" but Christopher A. Hall and Steven D. Boyer. Here are a few comments I found of interest:
God, according to Christianity of every stripe, is the supreme mystery, a blinding sun too bright to look at, but the source of illumination that allows us to see everything else on the landscape.
In every one of these passages, mystery is linked decisively with its revelation, its being made known, and yet the mystery does not cease to be mysterious as a result.
What organ or capacity or element in us could possibly be adequate to perceive or to convey the living God in all his fullness? Feeling? Aesthetic awareness? Conscience? Sensation? Intuition? Some distinctive “religious faculty”? If reason is not adequate to the task, what human capacity is more adequate?
But surely every human faculty that confronts the divine mystery will ultimately prove to be insufficient.
Every faculty may approach God. But every faculty must approach God as God — and this means that every faculty should expect to be overwhelmed and undone by a supremacy that cannot be mastered.
If God is really God, then recognizing a limitation of reason at just this point is really the most rational thing we can do.
As we become satisfied with any picture or image of God, we are in danger of idolatry.
Job recognizes that to understand God the Creator aright is always to confess that he is exalted beyond our understanding.
The biblical doctrine of God, then, moves easily from speaking of God as Creator to speaking of God as beyond knowledge.
In opposite images, we learn that God dwells in “a dark cloud” (1 Kings 8:12) but also in “unapproachable light” (1 Tim. 6:16). Either way, no one has seen God at any time (John 1:18), for no one can see his face and live (Exod. 33:20).
It looks as if creatures will always perceive an overpowering “otherness” in the Creator—and perhaps will perceive it best when the blinding obfuscation introduced by sin is finally removed. Recall that even the sinless angels in Isaiah’s vision must cover their faces and their feet in the presence of the thrice-holy God (Isa. 6).
God can be present in all of creation as no creature can, precisely because God transcends creation as no creature does.
God is so “other” that his otherness, unlike other othernesses, includes even sameness.
Any transcendence that is conceivable is shown by that very fact not to be genuinely transcendent.
It seems that the more fully God is revealed in Scripture, the more readily the human authors of Scripture acknowledge his unfathomable greatness.
The transcendent Lord is too exalted to be limited even by the category of transcendence. Hence, he is sovereignly free to make himself known.
We do know God, and not just in the nonrational experience of mystical ecstasy, but in the concrete categories of rational inquiry that his revelation unfolds.
Yet his hiddenness is itself part of what God has revealed about himself.
And we bow in deepest worship at just that point where we see most clearly that we cannot see clearly.
There is a genuine revelation that makes known the mystery of God, and there is also a genuine mystery that no revelation can dilute.