1 Corinthians 2:10-15

For God has unveiled them and revealed them to us through the [Holy] Spirit; for the Spirit searches all things [diligently], even [sounding and measuring] the [profound] depths of God [the divine counsels and things far beyond human understanding]. For what person knows the thoughts and motives of a man except the man’s spirit within him? So also no one knows the thoughts of God except the Spirit of God. Now we have received, not the spirit of the world, but the [Holy] Spirit who is from God, so that we may know and understand the [wonderful] things freely given to us by God. We also speak of these things, not in words taught or supplied by human wisdom, but in those taught by the Spirit, combining and interpreting spiritual thoughts with spiritual words [for those being guided by the Holy Spirit]. But the natural [unbelieving] man does not accept the things [the teachings and revelations] of the Spirit of God, for they are foolishness [absurd and illogical] to him; and he is incapable of understanding them, because they are spiritually discerned and appreciated, [and he is unqualified to judge spiritual matters]. But the spiritual man [the spiritually mature Christian] judges all things [questions, examines and applies what the Holy Spirit reveals], yet is himself judged by no one [the unbeliever cannot judge and understand the believer’s spiritual nature].