When I meet someone who is smarter than me I'm overjoyed. That's sort of how I face the question of who made God? Now, you're frustrated by that question. I'm delighted by it. It's the limit of the human mind. It's like an ant trying to comprehend driving a car. What was before the Big Bang? Was man seeded by aliens? Who made the aliens? There is no empiracle answer to that puzzle. We've hit the wall we cannot scale.
Now, you can drive youself nuts by banging your head against it. Or you can laugh with unrestrained mirth and be entertained. There is no way around it.
Concerning the indecipherability of the Powers that Be, I agree that reason fails. However, if this Power choses to make itself understandable it can certainly do so. I believe it has through the Holy Spirit and through Jesus as recorded in the Bible.
Why the Bible and not the Koran or some other book or tradition?
I think that, to a degree, that question can be answered through reason. Compare the lives of those who followed the one and others. Investigate via standard scholarship the claims. Look at the moral code that, I believe, is hardwired into every human heart and see what belief most reflects it.
Of course it will ultimately hinge on faith but that's true of any attempt to resolve the issue whether it's by the Resurrection or other dimensions.