Chapter four picks up on John’s mention of the Holy Spirit in 1 John 3:24. Paul wrote that the Spirit is God’s seal of salvation (Ephesians 1:13-14) and assurance of our relationship with God (Romans 8:16); John agreed. The Spirit is the internal evidence of knowing God, while our obedience is the external (3:24). One of the primary ways the Spirit works is that he changes our understanding and beliefs. In 1 John 4:1-3, John gave the test of “who Jesus is” as proof of the Spirit’s indwelling. Only a believer can fully agree with Jesus’ full deity and full humanity, and John wrote that anyone who fails that test comes from a spirit of antichrist, not the Holy Spirit. Our basic beliefs reveal our spiritual state (1 John 4:6).
Coming back to the theme of loving one another, John gave another proof of genuine salvation. Only those who are God’s children can exhibit God’s love (1 John 4:8). The reason is that, because a person cannot give what he does not have, and only a believer has experienced God’s love and grace (1 John 4:10), only a believer can share it. Thus, because we are recipients of God’s love, we are obligated to share that with fellow recipients (1 John 4:11). Not only is hating a fellow believer likened to murder (3:15), this ungodly action proves to be a lie, because we cannot love God while hating his family (1 John 4:20). Again, this is the standard that God calls us to, even though we do not always fulfill it faithfully. So, following the stark ideal, John couched it in language of obligation: “the one who loves God should love his fellow Christian too” (1 John 4:21).