Conviction of Sin. To understand the conversion work of the Holy Spirit, one may wish to separate His activities into three categories: pre-conversion, conversion, and post-conversion. In His pre-conversion work, the Holy Spirit goes before the Christian witness to prepare the hearts of non-believers so that they will turn to Christ when the gospel is delivered. In John 16:8, Jesus says that the Holy Spirit “convict[s] the world of guilt in regard to sin and righteousness and judgment.” The Holy Spirit exposes the sin of unbelief leaving people without excuse (John 15:22; 16:9). He will also light the path of righteousness for all mankind to see when Jesus is exalted to heaven (John 16:10). Since Christ’s exaltation, God’s Spirit convicts the world in regard to judgment because the sinfulness of the devil and all the descendants of Adam was exposed on the cross of Christ when the world put Him to death (John 16:11).

Repentance and Faith. In His conversion work, the Holy Spirit gives to [converts] gifts of repentance and faith by which they accept the Lord who is proclaimed and confess Him. Repentance, though it involves some human initiative, does not find its source in humanity; rather, God through the power of His Holy Spirit enables converts to repent of their sins (Acts 5:31; 11:18; 1 Th 1:5; 2 Tim 2:25). Therefore, repentance and forgiveness of sins are gifts of God’s Spirit. In Ephesians 2:8, Paul declares that faith is “the gift of God.” Since repentance and faith are both gifts of the Holy Spirit, conversion must be the work of the Holy Spirit; otherwise, converts will be able to make a claim that they have, in some way, merited their own salvation through their own effort (Eph 2:8; Titus 3:5).

Confession of Christ. The Holy Spirit’s role in conversion goes beyond the convert’s ability to respond to the Gospel in repentance and faith. Paul credits the Holy Spirit as the One who enables the convert to confess that “Jesus is Lord” (1 Cor 12:3). In Romans 10:9, Paul says that if one makes this confession and “believe[s] in [one’s] heart that God raised [H]im from the dead, [one] will be saved.” The salvation process, therefore, is dependent on the work of the Holy Spirit. No one can have a change of heart and turn to God unless the Holy Spirit does the changing (Rom 2:29; 2 Cor 3:3).

Changing the Human Heart. Paul argues in Romans 2:29 that a person is an Israelite (that is, a member of God’s chosen people) inwardly when the inner witness of the Holy Spirit is present in the human heart. Also in this verse, one learns that it is not the Law that changes one’s identity with God; rather, it is the presence of the Holy Spirit and His renewal of the heart that brings the convert into right relationship with God. In 2 Corinthians 3:3, Paul differentiates between the insensitivity toward God caused by sin under the old covenant and the responsiveness to God caused by inner renewal of the human heart performed by the Holy Spirit.

Indwelling the Believer. Not only does the Holy Spirit change the convert’s heart, He also indwells the heart of the believer (John 14:16-18; 2 Cor 1:22; Gal 4:6).