4 Bible Verses about Discernment, Source Of

But we [apostles] did not receive the spirit of the world [i.e., human wisdom. See verse 6], but the Holy Spirit from God, so that we could understand what was freely given to us from God [i.e., the gift of inspiration. See verses 9-10]. These also are the things we [apostles] speak, not in words taught by human wisdom, but [in words] taught by the Holy Spirit. We use [or, combine] Spirit-taught words to express [or, with] Spirit-given truth. Now the natural person [Note: Since this person is contrasted with the spiritual person of verse 15, it is taken here to mean the person without the Holy Spirit] does not receive the things [i.e., truths] revealed by the Holy Spirit of God, because they are [considered] foolishness to him. And he cannot understand them because they must be discerned by using spiritual judgment [i.e., judgment aided by the Holy Spirit].read more.
But the spiritual person [i.e., one who has the Holy Spirit] is able to discern all things [i.e., has the ability to make right judgments about things], and he himself [i.e., his conduct] cannot be [critically] discerned by any [unbelieving] man.

But "solid food" is for mature people, who because of using their [spiritual] senses, have become able to distinguish good from evil.

And you people must not be conformed to [the values and standards of] this age, but you should become transformed [i.e., changed in attitude and action] by having your mind renewed [i.e., to think in a totally different way]. Then you will be able to determine [and practice] God's will, the thing that is good, and acceptable and perfect.

[Isa. 40:13 says], "For who knows [what is in] the Lord's mind? And who is capable of instructing Him? But we have the mind of Christ. [Note: The "we" may refer to the apostles, who had the gift of inspiration (See verse 12), or to all Christians who have spiritual discernment].