Well, the thing is, the issues our Lord was writing about were real issues. For example, Nicolaitans were real heretics, who followed the Deacon Nicolas, ordained in the Book of Acts, who at some point decided that Christianity meant total sharing of property, and offered to share his wife with any who asked, and also embraced Gnostic theology derived from Simon Magus. Nicolaitanism became popular for the same reason Islam and Mormonism initially became popular and the cult of The Bhagwan Shree Rajneesh became popular - relaxed sexual morality. Nicolaitanism allowed wife swapping, Mormonism and Islam restored polygamy, which Christianity had suppressed, and Judaism had also phased out, and The Bhagwan encouraged his followers to be sexually promiscuous while mocking marriage as an obsolete institution. So our Lord despising its doctrines makes sense.
In interpreting it literally-historically, I am using the Antiochene exegetical method, which these days too many people use exclusively when interpreting the Old Testament, when it is filled with Christological and eschatological prophecy. When people attempt to apply the letters of Christ to churches of the present, or churches throughout history, or churches in the end times, that is the Alexandrian exegetical method, which is based on a prophetic or parabolic interpretation with a Christological and eschatological focus, using allegorical, typological, metaphorical, or mystagogical means.
I am, like the Cappadocians and St. John Chrysostom, and I would argue, our Lord Himself, who tended to interpret scripture literally and prophetically, sometimes the same passage, a proponent of using both methods, with the amount of literal-historical Antiochene interpretation and the amount of parabolic and prophetic Alexandrian interpretation that is appropriate being different for each part of the Bible, and sometimes varying within a given book, as well as the specific Alexandrian exegetical technique that should be used. And I think in general that the text itself will suggest the extent to which we should take it literally and the extent to which we should read it as prophecy. For example, it is clear that Jonah being forced overboard to save the ship while on a mission to save a gentile city, Nineveh, from destruction, makes him a type of Christ; his being in the belly of the whale for three days and three nights foretells the death and resurrection of our Lord; the repentance of the Ninevites which spares them from destruction is literally true, because Nineveh was an early center of Christianity and to this day, the Nineveh Plains of Iraq are the center of the Assyrian Church of the East and the Ancient Church of the East, and Assyrian nationalists have long desired them as a homeland for Syriac Christians; the Syriac Orthodox and Chaldeans also live there in large numbers; the repentence also symbolically points to the success Christianity enjoyed among the gentiles, while the continuing lack of faith on the part of Jonah suggests how some Jews would have difficulty accepting Christ despite overwhelming evidence; the near failure of Jonah as a prophet also shows how only our Lord, who was the Only Begotten Son and Word of God, devoid of sin, fully God and fully Man, could ultimately succeed in saving everyone. But I also believe the story was literally true, and that Jonah did survive in the belly of the whale, because God is omnipotent; his angels could easily have kept Jonah alive by protecting him from the digestion of the whale, and ensuring hid blood remained oxygenated, and by causing this to happen, our Lord ensured the Ninevites would listen, and also captivated the attention of the Jews.
And it should be noted that there is a hilarious section of the Talmud in which the Rabbis pause from their discussion of inheritance and other “thrilling” legal issues, and instead talk about various spectacular fish they had personally encountered. This to me shows how much, even centuries after Christ, the exoteric (outward, literal) meaning of Jonah still captured the imagination of the Jews, and I believe those who came to understand its exoteric, prophetic meaning became more receptive to the Gospel, the parallels between Christ and Jonah, as well as the differences, become too obvious to ignore, and Jonah was written many centuries before the Incarnation.
