3:1 John marveled at God’s love because of its effect—sinners can be called God’s children.
3:2 The world may think little of God’s children now, but at Christ’s return things will change. Believers will be transformed because they will see him as he is.
3:3 Knowing that the Lord will return is a strong incentive for believers to live in ways that are pleasing to him.
3:4 Sin is a grave matter because God has revealed his moral character in his holy law, and sin is lawlessness. It is a personal offense against God.
3:5 Verses 4 and 6 are veiled imperatives that warn by negative examples how John’s readers are not to conduct themselves. Verse 5 is the indicative that grounds the imperatives. The purpose of the incarnation was to take away sins. John’s statement affirms the sinlessness of Jesus (see 2Co 5:21; Heb 4:15).
3:6 John was aware that Christians sin (2:1). They can receive forgiveness through Jesus’s death (1:7) as they confess their sins (1:9). By everyone who sins has not seen him or known him, John had in mind flagrant sin by false “believers” whose confession of Jesus was false (2:23), whose love was set on the world rather than God (2:15), and whose obedience was lacking (2:4). Jesus himself warned about people who called him “Lord” and did great things in his name, but ultimately were not genuine disciples (Mt 7:21-23).
3:7 Satan continually seeks to subvert and deceive God’s people. We must be vigilant always.
3:8 When believers forsake sin, they thwart the devil’s aims and further God’s kingdom.
3:9-10 On does not sin, see note at v. 6. God’s seed is the gospel message. Believers are born of God by the work of his word, and this makes them able to do “what is right” (v. 7). Not able to sin means freedom from bondage to breaking God’s law and freedom to live as God’s children. John spoke of what spiritual rebirth makes obvious—not sinless perfection but a life surrendered fully to God.
3:11 Apostolic preaching emphasized that faith in a God of love moved believers to become people who love one another.
3:14 Our assurance of salvation rests in part on the love that God gives us for our brothers and sisters—that is, fellow believers. If we have this love, it is a sign of our salvation. If not, we are warned to examine our hearts before God.
3:15 There is no middle ground. Love is the gospel mandate (Jn 13:35). The person who neglects to love hates his brother or sister. This signals absence of eternal life. This verse recalls Jesus’s teaching in Mt 5:21-22.
3:17 Selfishness and God’s love are mutually exclusive.
3:18 With the phrase in action and in truth, John declared that faith which is only talk is false faith.
3:19 Before him refers to God’s observation of our lives. Faithful living results in confident hearts rather than guilt, evasion, or fear.
3:20 Human hearts can be self-deceived, but God who knows all things can grant assurance.
3:23 His command and faith in his Son Jesus Christ are not different things but two aspects of a single, undivided love of God.
3:24 The role of the Holy Spirit has been assumed all along in this epistle, but he is mentioned outright here for the first time.