The following is an excerpt from The MacArthur New Testament Commentary on 2 Corinthians 4.

or adulterating the word of God, but by the manifestation of truth commending ourselves to every man’s conscience in the sight of God. (4:2b)

Jesus Christ is truth incarnate; He Himself declared: “I am … the truth” (John 14:6; cf. John 1:14, 17; Rev. 19:11). When people look to Him for salvation, they fall in love with the truth; the lost will perish eternally “because they did not receive the love of the truth so as to be saved” (2 Thess. 2:10). Therefore being saved means loving the truth.

From his conversion, along with his hidden life of sin and shame, Paul also renounced any feeling of shame because of the offense of the gospel that might make him guilty of adulterating the word of God (cf. Phil. 1:20). Adulterating is from doloo, a word used in extrabiblical Greek to speak of corrupting gold or wine with inferior ingredients (Richard C. Trench, Synonyms of the New Testament [Reprint; Grand Rapids: Eerdmans, 1983], 230). Paul’s message was the plain, pure, unmixed truth of the gospel.

The same could not be said, however, for the false apostles. They were busy adulterating the Word of God for their own purposes. In 2 Corinthians 2:17 Paul denounced them as being guilty of “peddling the word of God.” They were con men, cheats, charlatans, and frauds, guilty of the same deception of which they falsely accused Paul. No doubt they accused him of tampering with the truth by not preaching the Mosaic Law. They probably also insisted that Paul’s simplistic message denied the hidden, secret things of God, that therefore he was guilty of failing to preach the whole counsel of God. Sadly, many today level the same charges at those who proclaim the sufficiency of Scripture. The idea that the Bible alone—apart from psychology, mysticism, or supposed supernatural experiences—contains everything needed to live a joyous, fulfilled, God-honoring life is derided as quaintly naïve and overly simplistic. Even sadder is the reality that many Christians “will not endure sound doctrine; but wanting to have their ears tickled, they … accumulate for themselves teachers in accordance to their own desires, and … turn away their ears from the truth and … turn aside to myths” (2 Tim. 4:3–4). The siren song of sophisticated false teaching lures many to make shipwreck of their faith.

A sure mark of a growing Christian is love for biblical truth. When there is an open, clear manifestation of the truth of Scripture, no matter what public scorn it brings, there is the source for spiritual power and impact. But when preachers, ashamed of the gospel, proclaim human wisdom deceitfully in the name of divine truth, their work is impotent. Thus, the faithful preacher’s world is the realm of biblical truth. His task is to proclaim the clear, pure doctrine that is the foundation of the faith. All believers should love the truth; they should “like newborn babies, long for the pure milk of the word, so that by it [they] may grow in respect to salvation” (1 Peter 2:2; cf. 1 Tim. 4:6).

Paul’s plain, straightforward preaching of the gospel had the effect of commending him to every man’s conscience. All people, even those who have not heard the gospel, have an innate (though limited) knowledge of God’s law. The preaching of the gospel activates the conscience, which bears witness to the truth of the message even in those who reject it. That is true because “the word of God is living and active and sharper than any two-edged sword, and piercing as far as the division of soul and spirit, of both joints and marrow, and able to judge the thoughts and intentions of the heart” (Heb. 4:12).

As with everything else in his life, Paul preached the truth in the sight of God. In 1 Corinthians 4:3–4 he wrote, “But to me it is a very small thing that I may be examined by you, or by any human court; in fact, I do not even examine myself. For I am conscious of nothing against myself, yet I am not by this acquitted; but the one who examines me is the Lord.” He sought God’s approval, not man’s, knowing that He is the One to whom every preacher (and every believer) is ultimately accountable.

The measure of a believer’s spiritual maturity is his or her loyalty to the truth (cf. Ps. 119:97–106; 113, 119, 127, 161–162, 174). Throughout its history, those who have had the greatest impact in the life of the church have been those most committed to the truth. And those who love it will find it in Jesus (Eph. 4:21).