Authorship, date, and background
2 John was written by "the elder," as was 3 John. The question of authorship depends upon identifying who "the elder" was. Studies of 1, 2, and 3 John clearly show that all were written by the same person. Some modern scholars do not think it was the apostle John. So far as the ancient church is concerned, it was said to be John, the son of Zebedee. Conservative scholars say with one voice that the Gospel of John and these three letters were all composed by the apostle. This letter and the other two were undoubtedly written in the city of Ephesus around A.D. 90.
Characteristics and content
The church has been plagued by false doctrine through the ages. It always dilutes the witness of believers, brings ill effects to those who accept it, and results in decay and decline in the Christian's personal walk. The person of Jesus Christ is at issue here. The specific question is whether Jesus became a true human being with a body like ours (7). John stresses the doctrine of Christ and thereby makes plain that Christianity is based upon propositions which are forever true. A departure from the foundational truths of the faith produces shipwreck. John calls such departures wicked and forbids believers to invite such a heretic into their homes; nor is such a one to be encouraged in any way. It is always possible for someone to affirm faith in what he does not really believe. Thus, there were then and are now hypocrites among true believers. But we can be certain that whoever denies the truth cannot be a Christian. Whoever does not love is not a true believer, however much he professes faith in doctrine; a person who denies basic doctrinal truths is unsaved and neither will he love.