What exactly is discernment? It means “to distinguish, to separate out by diligent search, to examine.”
Search…examine… “Now these Jews were more noble than those in Thessalonica; they received the word with all eagerness, examining the Scriptures daily to see if these things were so.” (Acts 17:11, emphasis added) The Berean Christians didn’t take Paul’s word for anything. They listened to his teaching and then they went to the scriptures to see if what he taught was true. Because the Bereans checked Paul’s teaching against Scripture, he commended them saying that they were “more noble than those in Thessalonica.”
Christians who are spiritually discerning are able to properly distinguish between true and false teaching. Those with discernment have wisdom. Moreover, in the Bible we’re told that a true believer possesses the mind of Christ. “The spiritual person judges all things, but is himself to be judged by no one. ‘For who has understood the mind of the Lord so as to instruct him?’ But we have the mind of Christ.” (1 Corinthians 2:15-16)
According to Bible expositor Matthew Henry:
The apostles were not guided by worldly principles. They had the revelation of these things from the Spirit of God, and the saving impression of them from the same Spirit. These things they declared in plain, simple language, taught by the Holy Spirit, totally different from the affected oratory or enticing words of man’s wisdom. The natural man, the wise man of the world, receives not the things of the Spirit of God. The pride of carnal reasoning is really as much opposed to spirituality, as the basest sensuality. The sanctified mind discerns the real beauties of holiness, but the power of discerning and judging about common and natural things is not lost. But the carnal man is a stranger to the principles, and pleasures, and actings of the Divine life. The spiritual man only, is the person to whom God gives the knowledge of his will. … And the apostles were enabled by his Spirit to make known his mind. In the Holy Scriptures, the mind of Christ, and the mind of God in Christ, are fully made known to us. It is the great privilege of Christians, that they have the mind of Christ revealed to them by his Spirit. They experience his sanctifying power in their hearts, and bring forth good fruits in their lives. (Source – bold added)
Only the spiritual man (regenerate) possesses the knowledge of God’s will….because he has the mind of Christ. Henry calls to our attention that it is through reading the scriptures that the spiritual man receives the knowledge of His will.