The Book of 1 John

1 John is written 'so that you may know that you have eternal life,' and it gives the church tests by which assurance stands or falls: walking in the light rather than the darkness, confessing rather than denying that Jesus Christ has come in the flesh, keeping His commandments, and loving the brothers. John writes in absolutes, light and darkness, truth and lies, children of God and children of the devil, because the gospel really does divide the world.

At the letter's heart is love defined by the cross: 'In this is love, not that we loved God, but that He loved us and sent His Son to be the propitiation for our sins.' These chapter-by-chapter commentaries trace the grounds of assurance, the marks of genuine faith, and the fellowship with the Father and the Son that is eternal life begun.