Man sees this world...plants, animals, the Earth, the Sun, the Moon, stars. He sees certain design in them...certain creation in them...certain order in them. He asks a question, who created it? He refers this unknown creator of orders as God. [Orders = God]
Man sees a fellow man gets sick and die. He doesn't know why or who does it. He also doesn't understand many things that happen around him. He could not find any reason, logic, or order. Though it looks random without any reason or logic or order, he concludes that it must be somebody doing it for some reason. He refers this unknown creator of disorders as God. [Disorders = God]
In general, whether the order that amazes him or disorder that confuses him, he refers unknown as God.[Unknown = God]
Later on, he discovers some reason behind some of the unknowns. He finds some logic and reason for some disorders and recognizes the order in it. He concludes all disorders must have some orders behind it. Now he looks for an order behind each and every disorder. He finds more and more orders behind many disorders. But he stumbles at certain inherent disorder (randomness). He tries harder and harder to find an order behind this inherent disorder.
Now he slowly sees a possible big picture. He finds a law of nature that concludes, a pure disorder (equilibrium) is the ultimate destiny of the universe. He recognizes how some orders (including galaxies, stars, planets, life, mind, etc.) can be created out of disorders temporarily; but ultimately leading towards its final destiny, a pure disorder. And hence he lives with some orders (predictable-s) and some disorders (unpredictable-s). Even if it is correct, he does not understand why nature follows this law. He continues his search!
In any case, he recognizes certain deep mystery in the universe when he looks for its ultimate origin, and wonders whether he could understand it fully. As usual, many jump to conclude this unknown as God. But few recognize that God is much bigger unknown than the unknown it tries to explain!
At the end, after all [God = unknown]. Does God exist? Yes, because unknown still exists! But God is not what you think it is, because it is unknown!