Who was the author? The Divinely-inspired author of 2 John is the apostle and evangelist St. John, who in the book refers to himself as the "elder", perhaps as the youngest apostle has outlived his generation.
What is the book? The book of 2 John is an apostolic epistle or "letter" written to the whole church, or any congregation, which he refers to as "the elect lady and her children", and so is classified as a "catholic" or "universal" letter.
Where was it written? The book of 2 John was likely written from Ephesus, although St. John's reference to "the children of your elect sister greet you" could refer to the believers in any church.
When was it written? The book of 2 John probably was written around the same time as 1 John, between A.D. 90 to 100 or 85 to 95.
Why? The epistle sternly warns against believers showing hospitality to or otherwise supporting false teachers and thereby being a part of those who pervert the Gospel.
How? The book of 2 John emphasizes many of the same themes as 1 John: the commandment of love, the reality of Jesus's incarnation, the designation of the false teaching as the work of the antichrist, and the insistence that the Father can only be accessed through the Son.
For further reading on the book of 2 John:
- Kretzmann, Paul E. Popular Commentary of the Bible: The New Testament, Volume II, The Epistles of the Apostle Paul, The Epistle to the Hebrews and the Catholic Epistles, the Book of Revelation. St. Louis: Concordia Publishing House, 1922. (There are 4 pages of comments on 2 John in this commentary.)
- Lenski, R. C. H. The Interpretation of the Epistles of St. Peter, St. John and St. Jude. Minneapolis, MN: Augsburg Publishing House, 1961. (There are 20 pages specifically on 2 John in this commentary.)