In the short space of this letter, John gives us a vital tutorial in the contrast between friends & enemies of the Gospel. Many modern Christians have no category for what Jesus meant when He commanded us to love our enemies. Broadly speaking, we have no clue we have enemies, we fail to recognize those enemies, and we have no clue that loving them requires us to confront their errors (Cf. Eph. 5:11, 2 Jn. 11).