Conviction is regret and remorse for sin that comes with the grace-enabled awareness that one is a sinner.
The second great lie that the Holy Spirit exposes is the lie that humans are not sinners (the first great lie is that God is not trustworthy or loving; more here). This lie only comes to light once the Holy Spirit assures us of the character of God—namely, his trustworthiness and love—by pointing to the cross. Rebellion against God is only criminal if God is good; otherwise, rebellion is noble. As the Holy Spirit reveals the goodness of God by pointing to Jesus and the cross, the rebellion of humanity is exposed as sin. It is only when rebellious humanity witnesses the goodness and holiness of God that there can be a sense of regret and remorse for sin. McCall writes,
We can begin to understand sin rightly only in relation to God—and thus to know sin better is to know God better to better understand sin is to better understand the justice, righteousness, and holiness of God. And to better understand sin is to better understand the glorious mercy of the triune God who nature s holy love.Tom McCall
Jesus said, “And when he [the Holy Spirit] comes, he will convict the world concerning sin and righteousness and judgment” (John 16:8). In convicting the world of sin, the Holy Spirit in the New Testament accomplishes what the Law accomplished in the Old Testament. The Holy Spirit, like the law, draws out sin (Rom. 5:12–14). Cranfield writes, “It is only in the presence of the law, only in Israel and in the church, that the full seriousness of sin is visible, and the responsibility of the sinner stripped of every extenuating circumstance.”
What the Law accomplishes externally in revealing sin, the Holy Spirit accomplished internally. The will of God, through the indwelling presence of the Holy Spirit, transcribes the will of God on the hearts of believers so that when they have committed sin, or are being tempted to sin, they know it intuitively as informed externally by the Scriptures.
The illuminating ministry of the Holy Spirit is evident in the symbol of fire (Acts 2:1–4). The Holy Spirit, like fire, reveals. One of the fatal mechanisms of sin is that it remains hidden. It hides in the dark. By hiding, sin convinces sinners that there is nothing wrong. Sin is the normal. Sin makes sure that we stay in the habit of measuring behavior, attitudes, and thoughts against other sinners rather than against God’s special revelation of his intentions for human life through Jesus and the Scriptures. First John 1:8 says, “If we say that we have no sin, we deceive ourselves, and the truth is not in us.” It is by grace-enabled invasion of the Holy Spirit in our lives that our eyes are opened to the fact that we are sinners. Once the goodness of God comes rushing into our midst, so does the awareness of our sinfulness (Is. 6). The Apostle Paul writes to the Ephesians:
Now this I affirm and insist on in the Lord: you must no longer live as the Gentiles live, in the futility of their minds. They are darkened in their understanding, alienated from the life of God because of their ignorance and hardness of heart. They have lost all sensitivity and have abandoned themselves to licentiousness, greedy to practice every kind of impurity. That is not the way you learned Christ! For surely you have heard about him and were taught in him, as truth is in Jesus. You were taught to put away your former way of life, your old self, corrupt and deluded by its lusts, and to be renewed in the spirit of your minds, and to clothe yourselves with the new self, created according to the likeness of God in true righteousness and holiness.Ephesians 4:17–24; italics added
Paul points out that sinful behavior originates in the mind/heart (“mind” in the NT is often synonymous with what the “heart” is in the OT). Paul describes the contrast between the empty minds of pagans, and Christians who have “learned,” “heard,” and were “taught.” The Holy Spirit as the illuminating fire brings light to darkened minds and hearts; he reveals God’s will to believers (John 14:26). The Holy Spirit is the means through which believers can know what God wants and expects. Paul says in Romans 12:2, “Do not be conformed to this world, but be transformed by the renewal of your mind, that by testing you may discern what is the will of God, what is good and acceptable and perfect.”
Paul also points out in the above passage that having a darkened mind is synonymous with alienation from God. First John 1:5–7 says:
This is the message we have heard from him and proclaimed to you, that God is light and in him there is no darkness at all. If we say that we have fellowship with him while we are walking in darkness, we lie and do not do what is true; but if we walk in the light as he himself is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin.John 1:5–7
In other words, being simply forgiven of sin without being filled with the Holy Spirit is undoubtedly less than God’s intentions for humanity. The human problem begins with the human heart’s separation from God. As the Holy Spirit restores the presence of God internally to humans, the sun rises on the human heart.
The Holy Spirit not only reveals sins, he they also reveal the sin nature. That the Law and the Holy Spirit reveal the sin nature is at the heart of Romans 7. Paul highlights in this passage that the Law draws out hidden sin in the life of God’s people. The Holy Spirit not only uncovers the human inability to overcome sin, but also reveal that the human condition is the result of a distortion that penetrates the deepest caverns in the human nature. The absence of God in the human heart creates such a distortion on the human condition that when something as good and pure as the Law comes along, rather than correcting the problem, humanity looks to it as a source for ideas on what not to do. The Law piques the interest of our carnal nature. Paul says in Romans 7:5, “For while we were living in the flesh, our sinful passions, aroused by the law, were at work in our members to bear fruit for death” (emphasis added).
In a much broader sense, we learn from the unusual reality of desires aroused by the Law that we are a rebellious people. Sin is not merely about fulfilling the desires of the flesh as it is about rebellion. Rebellion is the most satisfying desire of the flesh to satisfy—to demonstrate to the world that we are our own master; that we are free, independent beings. It is in the human nature to push back, to resist. How would sinners discover this if there were no Law to attempt to reign over them? It is by the establishment of rules over sinners that the natural impulse to rebel is uncovered.
The Holy Spirit’s work in revealing the sin nature leads to an awareness of the need for a new nature in Christ. The Holy Spirit not only brings an awareness of the need for forgiveness, but ultimately a rebirth, both of which the Holy Spirit accomplishes in the life of the believer. The Holy Spirit—by dwelling in believers and convicting hearts of sin and empowering obedience—imparts the righteousness of Christ to believer. The Holy Spirit delivers from the condemnation of being held captive to a diseased nature as Paul describes in Romans 6:1–11. In this passage Paul is not merely addressing escape from final judgment, he is also addressing the reality of present deliverance from the destructive behavior generated out of a depraved heart. Paul is talking about the indwelling of the Holy Spirit that is able not only to forgive sins, but to restore the image of God in humanity. The image of God restored in humanity (i.e., holiness), is a witness to the moral character of God in the world.
Again, Thomas McCall helps us conclude the matter of the conviction with this statement:
For although we find that recognition of the reality of sin is unavoidable, given observation of human experience, and although we can learn much about sin by the study of that human experience, we cannot have an adequate understanding of it precisely as sin apart from divine revelation and the theological reflection that is made possible by that revelation.Tom McCall
The revelation that McCall refers to here is administered by the Holy Spirit.
 Timothy C. Tennent and Ajith Fernando, For the Body: Recovering a Theology of Gender, Sexuality, and the Human Body (Grand Rapids, MI: Zondervan, 2020).
 See Isaiah 6.
 McCall, Against God and Nature, 31.
 Michael Bird citing Cranfield in The Story of God Bible Commentary: Romans (Edited by Tremper Longman III and Scot McKnight; Grand Rapids: Zondervan, 2016), 181; italics added.
 McCall, Against God and Nature, 27.