“Reformed theology holds that God can be known, but that it is impossible for man to have a knowledge of Him that is exhaustive and perfect in every way. To have such a knowledge of God would be equivalent to comprehending Him, and this is entirely out of the question: ‘Finitum non possit capere infinitum.’ Furthermore, man cannot give a definition of God in the proper sense of the word, but only a partial description. A logical definition is impossible, because God cannot be subsumed under some higher genus. At the same time it is maintained that man can obtain a knowledge of God that is perfectly adequate for the realization of the divine purpose in the life of man. However, true knowledge of God can be acquired only from the divine self-revelation, and only by the man who accepts this with childlike faith. Religion necessarily presupposes such a knowledge. It is the most sacred relation between man and his God, a relation in which man is conscious of the absolute greatness and majesty of God as the supreme Being, and of his own utter insignificance and subjection to the High and Holy One. And if this is true, it follows that religion presupposes the knowledge of God in man. If man were left absolutely in the dark respecting the being of God, it would be impossible for him to assume a religious attitude. There could be no reverence, no piety, no fear of God, no worshipful service.” (Louis Berkhof)
For more on the subject, visit the Systematic Theology page.