Paul Tillich - The ultimate Ground of Being

"The wisdom of all ages and of all continents
speaks about the road to our depth."  
"It has been described in innumerably different ways.
But all those who have been concerned -
mystics and priests, poets and philosophers,
simple people and educated -
with that road through confession, lonely self-scrutiny,
internal or external catastrophes, prayer, contemplation,
have witnessed to the same experience.
They have found they are not what what they  believed themselves to be,
even after a deeper level had appeared to them below the vanishing surface.
That deeper level itself became surface,
when a still deeper level was discovered,
this happening again and again, as long as their lives,
as long as they kept on the road to their depth."

"The name of this infinite and inexhaustible depth and ground of all being," "is God.
That depth is what the word God means. . . .
For if you know that God means depth, you know much about him.
You cannot then call yourself an atheist or an unbeliever.
For you cannot think or say: Life has no depth! Life itself is shallow.
If you could say this in complete seriousness, you would be an atheist;
but otherwise you are not.
He who knows about depth knows about God."

 

[Paul Tillich, "The Shaking of the Foundations"