There are certain criteria an ancient document may be subjected to in order to test it’s veracity. For example, one of these would be it’s internal consistency. Is the text internally consistent? Does it contain logical contradictions? Another is it’s historical accuracy. The Bible is actually remarkably accurate historically. Through the discipline of archeology, to this day we are yet to discover one single historical contradiction. All the ancient geographical locations, city’s, people groups etc that the bible refers to have all been confirmed to have actually existed. It is also highly internally consistent, particularly given that it was written by 40 different authors over a period of some 1500 years. It actually reads like one book, with a consistent overarching theme throughout.This alone is convincing evidence that it was ultimately authored by someone with a higher intelligence and purpose than a mere random collection of men, with each one penning out their own delusional ideas.
Another area we can look at is the manuscript evidence. There are over 24,000 partial manuscripts and 5,000 complete manuscripts of the Greek NT; far more than the next best, Homer’s Iliad, which has about 630 copies. In other words, if you want to question the accuracy of the Bible, you should also question the accuracy of all other ancient documents pre 1000AD. If we can’t be sure the Bible is accurate, we can’t be sure Alexander the Great existed either. Or Plato, or Aristotle for that matter. In fact most scholars estimate there are, at most, 400 words out of the entire NT text that could be disputed, and none of these are critical to any of the essential Christian doctrines.