One example of the utterly fallacious reasoning used to prove the inspiration of the bible is the internal harmony of all the books written by different authors. I find it surprising that theists can't see through this ruse. Given that the bible was written by different authors who lived at different times wrote their books years apart isn't it very likely that the authors of later bible books would have had access to and read the earlier bible books? For example, isn't it likely that the author of Revelation would have had access to and read Genesis? And having been educated by what he read in Genesis and believing it to be true, should it be surprising that the author of Revelation would think and write Revelation in a manner consistent with the "education" he received from Genesis and pre-existing bible books? So it's to be expected that each bible writer who would have read and believed what was written in the preceding bible books would have had their minds shaped by that information and would only naturally write their own books in a manner consistent with thinking shaped by preceding books.
By way of an example, a person who has studied the subject of evolution and believes it, would go on to write a book that is in harmony with current scientific thoughts on the subject of evolution. If you were to pick up that person's book and compare what it says with what is said in other scientific books on the subject of evolution, you would notice harmony. Are you to conclude from that the all those books were inspired by the same divine author because that's the only explanation for the harmony despite there being different writers? Of course not! How ridiculous!
For the internal harmony argument to have any merit, this is what would have had to have happened: All the bible writers would have had to write their books at the same time in different locations and not being aware of the contents of each other's books at the time of writing their own books. If that were the case then we could give merit to the internal harmony argument being evidence of divine inspiration - but not when writers wrote their books years apart and would have had access to preceding books, so as to make any harmony be explanable by purely natural means.