St. John Chrysostom depicts the difference between the gift of Christian knowledge and the darkness of the pagan, and of anyone who lacks faith in God and in all things of the spiritual world.
"The one who sees sees everything, even what pertains to the blind man. But none of the blind sees what pertains to the one who sees. So it is here also. We know both our own things and all that pertains to unbelievers, but they do not know ours.
For we know the character of present things and the dignity of future things. We know what will later happen to the world, what punishment sinners will undergo, and what the righteous will enjoy.
We know that present goods have no worth, and we expose their nothingness. But future goods are eternal and unchangeable. The spiritual man knows all this.
He also knows what punishment the psychic man will undergo in the life to come, and what the believer will enjoy. But the psychic man knows none of these things."
According to St. Theophan's explanation, "the psychic man is one who wants to know everything by his own mind. He acknowledges as true only what seems so to him.
He arranges his life and all his undertakings by his own methods, relying on them alone as on a firm foundation.
He sets earthly repose and happiness as the aim of life, and turns everything into a means toward that aim.
He has grown so accustomed to what is tangible and felt that he does not even consider the invisible and spiritual to exist.
Given such opposition between the disposition of the psychic man and the demands of the spiritual wisdom of God, it is very natural that he accepts nothing from those demands.
The utterances of the Spirit cannot be contained by him. They seem foolishness to him, and he can understand nothing in them.
To understand and grasp spiritual things, and to behold wisdom in them, the psychic man must cease to be such. Or at least he must begin to desire this."