John's writings are both ethereal and practical. On the one hand he deals with some of the most profound truths of the Christian gospel and then brings us up short with his black and white statements concerning who is 'in' and who is 'out'.
The dialogues between Jesus and the Pharisees in this gospel sound very harsh to a Western ear there are no punches pulled. But these are surrounded by miracles and healings, and the profound 'I Am' statements that fall from the pages and cause us to watch and listen in awe and wonder. We see the same contrast of profundity and practicality in John's letters as he speaks of Jesus in hushed tones and then condemns those who reject Jesus as 'antichrist'.
John makes the purpose of his gospel clear (John 20:31). He does it in such a way that tells and paints an unmistakable portrait of Jesus: that people come to know who He is and put their faith in Him.
In his letters, John aims to deal with error concerning the person of Jesus and to ensure the church remains on track. At the centre of all John's writings is a simple message to the Church: love one another.