Who was the author? The book of 1 John was authored by the Holy Spirit through the apostle and evangelist St. John.
What is the book? The book is an apostolic letter, or "epistle", written to the Church in general, thus its placement in the category of "catholic", "universal", or "general" letters.
Where was it written? John apparently lived for an extended period of time in Ephesus, from where he is thought to have written this epistle.
When was it written? The book of 1 John is thought to have been written between A.D. 90 and 100, or perhaps between 85 and 95.
Why? John seems to write to combat an early form of Gnosticism, one of the most dangerous false teachings of the early church period. Gnosticism considered the spirit good and matter evil and thus taught falsely about human beings, salvation, Christ, and the Christian life.
How? The book of 1 John is said to exhibit a "white-hot passion for the truth", summoning the church to penitence as it reflects on the antitheses of truth-lie, Christ-antichrist, and God-devil. In brief and pointed statements, John makes it clear where the church can and must stand enabled by God. No other similar book is said to furnish so many brief sayings that people can keep in their hearts "to live by and to die on."
For further reading on the book of 1 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 22 pages of comments on 1 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 183 pages on 1 John in this commentary.)