The chief trouble-maker in Ephesus was a man named Cerinthus. He had been influenced by Gnostic ideas concerning the relation between spirit and matter, and as a result developed wrong beliefs concerning Jesus Christ.
Believing God to be pure and matter to be evil, he denied that Jesus Christ could be heavenly and earthly at the same time. This led to a variety of wrong teachings. Some of these denied the full deity of Jesus, and others denied his true humanity (1 John 2:22; 4:2-3). Many Christians became uncertain of their salvation; for if the Jesus who lived and died in this world was not at all times fully divine and fully human, how could his death benefit people or satisfy God? To reassure Christians in their understanding of Jesus and the salvation he brought them, John wrote firstly his Gospel (John 20:31), and then the letter known as 1 John (1 John 5:13). Gnostic ideas concerning spirit and matter, besides leading to wrong teaching about Jesus, led to wrong behaviour among believers. Cerinthus taught that the behaviour of the body could not affect the purity of the soul, and therefore believers could sin as they wished. John condemned such teaching (1 John 3:6). He emphasized that Christians must be obedient to God, must love others and must be disciplined within themselves.
Contents of 1 John From
the beginning of his letter, John emphasizes the two areas of Christian truth that were under attack – the eternal godhead yet full manhood of Jesus Christ (1:1-4) and the obligation on Christians to live pure, disciplined, obedient lives (1:5-2:6). All Christians are to follow Christ’s commandment to be loving, and are to resist the pressures upon them from an evil world (2:7-17). God’s people must recognize that those with wrong teaching about Jesus Christ are of the devil (2:18- 29), and so too are those who encourage Christians to sin (3:1-10). Behaviour is the test of the genuineness of a person’s Christianity (3:11-24). Though steadfastly resisting error (4:1-6), Christians must consistently develop love, and in so doing they will become more assured in their salvation (4:7-21). Right belief is also necessary for assurance (5:1-5), and this belief centres on the uniqueness of Jesus Christ and his work (5:6-12). The practical results of assurance will be effectual prayer and victory over sin (5:13-21).