Why can't an unbeliever know the things of the Spirit of God?
The natural man, or unsaved person, does not receive the things of the Spirit of God. They are foolishness to him, and he does not want to comprehend them. Because these things are spiritually discerned or understood, he cannot know them.
Les explains that believers can understand the Scriptures and compare Scripture with Scripture, but the unsaved person cannot see where these things are connected. Paul calls the unsaved person the natural man, who receives not the things of the Spirit of God ([s82]-[s84]). Les notes the unbeliever may understand a few things, such as the story of Bethlehem, but when it comes to the deep doctrinal aspects of the Word of God, it is a closed book; end-time prophecies are also a closed book ([s87]-[s96]). Why doesn't he comprehend? Les says he doesn't want to, and it is all foolishness to him ([s104]-[s108]). Unsaved neighbors may think something is wrong with someone who goes to a weeknight Bible study ([s109]-[s117]). Consequently, since all of this is foolishness to the unbeliever, he cannot know them because these things are spiritually discerned or understood ([s118]-[s121]).
But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned.