When I was first in seminary, there was a class that loomed large in the MDIV Handbook - Christian Anthropology - which included intensive study of Paul Tillich.
Only 2 years out from the concussion that changed my life, having just completed my divorce in 2013, and still very much in the healing process, I was unsure if I'd be able to read the complex writings of this 20th Century Systematic Theologian.
Although his material is dense (understatement), I quickly discovered that my new post TBI brain consumed Tillich's every word, especially his use of polarity and paradox. He wrote like I painted, and I loved it.
The discussion below of God as beyond anything that humans can put into a box of objective certainty is a favorite topic that Tillich explores - It's God beyond human understanding ~ God as Mystery ~ Asymptotic Grace ~ Unobjectified ground into which the cane extends just beyond the finite edge of what is objectively known.
It's the courage that appears in the anxiety of doubt. It's so much bigger than a bearded guy in the sky...A worthy read.
"The question of the existence of God can be neither asked nor answered. If asked, it is a question about that which by its very nature is above existence, and therefore the answer - whether negative or affirmative - implicitly denies the nature of God. It is as atheistic to affirm the existence of God as it is to deny it.
God is being-itself, not A being.
On this basis a first step can be taken toward the solution of the problem which usually is discussed as the immanence and the transcendence of God.
As the power of being, God transcends every being and also the totality of beings - the world. Being-itself is beyond finitude and infinity; otherwise it would be conditioned by something other than itself, and the real power of being would lie beyond both it and that which conditioned it.
Being-itself infinitely transcends every finite being. There is no proportion or gradation between the finite and the infinite. There is an absolute break, an infinite “jump.”
On the other hand, everything finite participates in being-itself and in its infinity. Otherwise it would not have the power of being. It would be swallowed by nonbeing, or it never would have emerged out of nonbeing.
This double relation of all beings to being-itself gives being-itself a double characteristic. In calling it creative, we point to the fact that everything participates in the infinite power of being. In calling it abysmal, we point to the fact that everything participates in the power of being in a finite way, that all beings are infinitely transcended by their creative ground."
Paul Tillich, Systematic Theology, Vol 1