Published in 1678, The Pilgrim's Progress from This World to That Which Is to Come by John Bunyan [1628-1688] is a Christian allegory. Innovative because it was the first book to combine "a ripping yarn with the Gospel truth."
A poor tinker, Bunyan was a pioneer of the extension of the diary to spiritual autobiography and laid the groundwork for the novel.
From depression to rebirth; textbook guide to salvation. If a wretched sinner like Bunyan could be saved, there was hope for all.