First John is the Book of Fellowship. Practical teachings on the Christian walk are given by the last living Apostle. Walking in the light, and walking in fellowship with the Father and the Son are dominant themes. Many antichrists have gone forth into the world, and John urges his hearers to remain faithful to the witness that they have received from the Disciple Whom Jesus Loved.
“Of John” is named for the author of the epistle.
Although the text itself does not name the author, the unanimous witness of the Church Fathers quotes this epistle and ascribes it to John the son of Zebedee. Most valuable is the witness of Polycarp, the disciple of John, and likely “the angel of the church in Smyrna.”