To write a convincing novel about “What if the last apostle was still alive,” I’ve spent a lot of time researching John and the first century of Christianity. Of course, the bible is the primary resource. Here are just a few of the others I found helpful:
The Greco Roman World of the New Testament Era: Exploring the Background of Early Christianity, by James Jeffers. My favorite resource on what life was like in the time of John. Read this and you’ll have a better understanding of the context of the New Testament.
John, the Son of Zebedee: The Life of a Legend, by Alan R. Culpepper. Excellent book on the apostle John. Everything from the facts to legends–very interesting legends
Everyday Life in New Testament Times, by A.C. Boquet What was it like to live in the time of Jesus and his disciples? Boquet provides great detail.
The Beloved Disciple—His Name, His Story, His Thought: Two Studies from The Gospel Of John, by Vernard Eller. Is the apostle John the Beloved Disciple mentioned in the Gospel of John? Even though most biblical scholars assume it is, Vernard Eller makes an interesting case that it is another well known New Testament figure.