The Book of John is one of four books that sets forth the four-fold earthly-life and death and resurrection of the Lord Jesus Christ. John does not contain everything that Jesus said and/or did. It emphasizes the Lord Jesus Christ being God's son, who is the fulfillment of the Word that God spoke regarding the Christ, which is first recorded in Genesis 3:15.
John was one of Jesus' learning-disciples. He wrote this book after the resurrection and ascension of the Lord Jesus Christ into heaven and after the out-pouring of holy spirit on the day of Pentecost (refer to Acts 2). In Galatians 2:9, Paul wrote that John (along with James and Peter) was considered to be a pillar within the church and a minister to the holy-people (Christians) with a Judean/circumcision background.
