Almost from the time of their establishment, the churches in and around Ephesus had been troubled by false teaching. Paul had warned of such trouble (Acts 20:17,29-30), and his letters to Ephesus and Colossae show that major problems soon arose (Eph 5:6; Col 2:4,8,18). These problems increased over the decades that followed, and early records indicate that the person most concerned with correcting them was John, possibly the last surviving member of the original twelve apostles. John apparently lived in Ephesus, and wrote his Gospel and letters partly to deal with the false teaching of the Ephesus region (John 21:24; 1 John 2:26; 4:3; 2 John 7).
However, John was concerned with more than just opposing false teaching. A central purpose of his Gospel was to lead people to faith in Christ, so that they might experience the fulness of eternal life that Christ made possible (John 3:15; 6:27; 10:10; 20:31). A central purpose of his three letters was to reassure troubled believers of their possession of this eternal life, so that they might enjoy it fully in fellowship with God and with one another (1 John 1:3; 3:18-19; 4:13; 5:13; 2 John 5).
Teaching about Jesus Christ
John’s reason for wanting to reassure the Christians was that many of them had become confused. False teachers were spreading ideas that were part of a developing Gnosticism, a destructive heresy that reached its full expression in the second century.
Gnosticism (from the Greek gnosis, meaning ‘knowledge’) tried to explain some of the mysteries of life by combining Christian belief with pagan philosophy. In particular, it was concerned with harmonizing things between which there appeared to be some tension, such as spirit and matter, body and soul, good and evil. This led to damaging false teaching in relation to the person and work of Jesus Christ and the salvation and behaviour of Christians. (For further discussion on Gnostic-type teachings of the region see background notes to Colossians.)
Because the false teachers believed that a perfectly good God could not come in contact with an evil world, they refused to accept that divinity and humanity were perfectly united in Jesus Christ. As a result they denied that the Son of God became a man and died on the cross. John saw this as an attack on the very basis of Christianity and he openly denounced the false teachers. He insisted that if they refused to accept either Christ’s true humanity or full deity, they were not followers of Christ but enemies (1 John 2:18-19,22; 4:1-3).
Gnostic-type teachings also created problems in relation to everyday behaviour. The Gnostics asserted that those who accepted their teachings entered a spiritual realm that placed them above ordinary people. The evil of the material world could no longer affect the purity of the soul, and therefore people were free to express themselves without the need for self-control. The result was much immoral behaviour. This, said John, was further evidence that such people were not Christians, even though they mixed in Christian company (1 John 2:4; 3:6,8). True Christians were self-disciplined, obedient to God’s commands, and considerate of other people (1 John 2:6; 3:3,17; 5:3).