John’s epistles can be tricky to follow. To a casual reader things like “if we say we have no sin, we deceive ourselves,” followed by “I am writing these things to you so that you may not sin,” can be confusing. We need some context.
People who study and compare John’s Gospel with the epistles believe that John’s community of congregations was facing a multifaceted theological challenge. If we realize that the epistles were written to a network of house churches that needed help with their teaching, things become a little easier to understand.
It seems that there were at least four schools of thought in the churches. First there was a group of Jews who embraced Jesus and John’s teaching, but struggled to see Jesus as truly divine. Then there were the Greeks who had a dualistic view of the world and had a hard time believing that Jesus could be flesh and still be good. People who had the correct, paradoxical understanding of Jesus being fully man and fully God were stuck in the middle. Finally, there was a group or groups of people who were leaving the churches to embrace completely deviant teaching.
John’s epistles (and the Gospel) were written in part to address these challenges. This explains why they at times argue against two opposing errors.
Reading 2 John and 3 John (the only books that can truly be called letters) really helps us see this tension. 2 John was written to a congregation exhorting them not to follow the false teachers. 3 John is addressed to a house church leader, encouraging him to stand up to a fellow, misled, leader and to embrace Christians from other fellowships who share sound doctrine.