How is Leviathan a whale, that breathes fire? What would be the point of Jesus coming back to earth to kill a god damn whale
Leviathan is only mentioned five times in the Bible, all in the Old Testament: Job 3:8, Job 41, Psalms 74:14, Psalms 104:24-26, Isaiah 27:1.
If you have a New Testament translation that calls the beast or dragon in Revelation "Leviathan", then you may want to check and see if it was written by the Watchtower Bible Tract Society who has a bad habit of purposely mis-translating the text to fit their own agendas.
Although it can be easily confused.
The Hebrew for Leviathan used in the Old Testament is לויתן (livyathan) which means a large serpent, crocodile, or large sea creature. The Greek word for "dragon" used in the New Testament in Revelation is δράκων (drakōn) which literally means dragon or a great serpent.