The Gospel of John takes the form of an ancient biography—not a modern one, but an ancient one. First John is not a letter; it’s a sermon, it’s a homily on major ethical topics like love and sin. Second and Third John are, however, prototypical letters that are like other ancient letters. And then we have the book of Revelation, which is in fact apocalyptic prophecy with an epistolary framework—so there is a letter bit at the beginning and a letter bit at the end, and in between, we have John’s visions.