First Epistle of John
Also he says that as true Christians they would "not practice sin" (keep sinning) (Chapter 2, verse 1); that "we should love one another" (Chapter 3, verse 11); and that "you who believe in the name of the Son of God... may know that you have eternal life." (Chapter 5, verse 13). So we see that the aim of the letter was to make the Christians more full of joy, and also to help readers to know if they are really saved.