The object of our worship is the One God, He who by His commanding word, His arranging wisdom, His mighty power, brought forth from nothing this entire mass of our world, with all its array of elements, bodies, spirits, for the glory of His majesty; whence also the Greeks have bestowed on it the name of Κόσμος. The eye cannot see Him, though He is (spiritually) visible. He is incomprehensible, though in grace He is manifested. He is beyond our utmost thought, though our human faculties conceive of Him.
He is therefore equally real and great. But that which, in the ordinary sense, can be seen and handled and conceived, is inferior to the eyes by which it is taken in, and the hands by which it is tainted, and the faculties by which it is discovered; but that which is infinite is known only to itself. This it is which gives some notion of God, while yet beyond all our conceptions— our very incapacity of fully grasping Him affords us the idea of what He really is. He is presented to our minds in His transcendent greatness, as at once known and unknown.
And this is the crowning guilt of men, that they will not recognize One, of whom they cannot possibly be ignorant. Would you have the proof from the works of His hands, so numerous and so great, which both contain you and sustain you, which minister at once to your enjoyment, and strike you with awe; or would you rather have it from the testimony of the soul itself? Though under the oppressive bondage of the body, though led astray by depraving customs, though enervated by lusts and passions, though in slavery to false gods; yet, whenever the soul comes to itself, as out of a surfeit, or a sleep, or a sickness, and attains something of its natural soundness, it speaks of God; using no other word, because this is the peculiar name of the true God.
“God is great and good”— “Which may God give,” are the words on every lip. It bears witness, too, that God is judge, exclaiming, “God sees,” and, “I commend myself to God,” and, “God will repay me.” O noble testimony of the soul by nature Christian! Then, too, in using such words as these, it looks not to the Capitol, but to the heavens. It knows that there is the throne of the living God, as from Him and from thence itself came down.
Source: The Apology (New Advent)