As Masked Man said, but I'd like to expand upon this, which is textual criticism. I'm by no means an expert on it, but I have done a lot of studying over the past year on it. Some groups ascribe to the "infallible word of God" in which scripture is "divinely inspired by God," and therefore, it means what it says, no more, no less. You'll find varying degrees of literalism and metaphorical. I have met many Christians who view the Old Testament entirely literally, and I have met Jews who see it entirely metaphorically. I think it is wrong to do either as there is so much history and context to consider that looking at the whole can be confusing and misleading - as many religions are.
Here are things to consider: The Old Testament was written after hundreds of years of oral history by Jews. These were also written in a Jewish-specific culture and, as such, have Jewish meanings and idioms. The first five are traditionally ascribed to Moses, but if he did dictate them, the earliest copies we have happened long after his existence. The other books have various authors and oral traditions leading up to their writings. The Bible is an anthology written by many different others, translated by many different scribes over many different centuries. We also have proof that passages were sometimes changed to fit certain cultures' ideas about the bible (thanks to modern technology, like, don't quote me on this MRI Imaging (could be another thing)). Going deeper than anyone probably wants to, but I'm too focused on the subject to dictate otherwise:
For example, the Hebrew Sheol is the traditional underworld of the Jews. In English, however, this place is translated into not just multiple different words (ex: Hell) but even phrases (ex: Realm of the Dead) across multiple different translations. Sheol is not the fire and brimstone underworld we commonly would think of, but instead a kind of nothingness and silence slumber. The Witch of Endor (yes, like Star Wars), for example, uses necromancy to summon the spirit of the prophet back from Sheol in the Old Testament. He is understandably miffed at this heresy and asks essentially, "Why, pardon my French, the hecky heck did you bring me back from the dead? I was at peace." Obviously, I paraphrase quite a bit and lean into comedy, but anyway, Christian theologians and translators often struggle with dealing with Sheol and its pre-Christ meaning in the "grand design," if you will. There are probably quite a few who do deal with this - again, not an expert or theologian, just things I've encountered in a year of study.
Also, in the Old Testament, there are over 30 names and words for God. Those in particular to keep track of are El (singular), Elom (dual), and Elohim (plural). Elohim is the term used at the beginning of Genesis for God. I have seen arguments that this is an example of the Canaanites polytheism, that this is an example of early Jewish Henotheism (many gods, but one is king above all), and that it is the royal plural for singular deity. Elohim, however, is also used in certain passages to refer to "angels" and the "divine council of god" (which, as far as I know, are assumed to be other angels). I'm not here to tell you what's right, only to point out the transcriptional problems of trying to understand a culture from several thousand years ago.
Going into the New Testament - as Masked Man said - the earliest copies we have of the Gospels are decades after Jesus' crucifixion. The Synoptic Gospels (meaning "same vision" - Matthew, Mark, and Luke) share sources of information and overlap in telling with certain things told differently (even if they're being as truthful as they can, let's remember human memory is far from infallible). John fills in details and stories that the others don't - John is also a smug son of a gun who refers to himself "as the one Jesus loved," if I remember correctly. Anyways, yeah written decades after the fact, as far as we can tell.
The their is Acts, which is the same author as Luke, both by tradition and as far as historians can tell. Things get sticky with Paul of Tarsus. Paul is technically the founder of what we would consider Christianity the religion. Jesus of Nazareth was a Jew and wasn't seeking to make a new religion but to spread his message to those who would hear it (first the Jews, then the Gentiles (non-Jews)). Paul (or at least the person claiming to be Paul) wrote for sure eight of the New Testament books and epistles. The other, particularly the most controversial, is Hebrews. I remember that it's for a specific passage.
Another thing is the Bible as we know it (which there are two major English versions, not including translations) wasn't solidified until several hundred years later by "the Church," which was really a council of various clergymen from many different sects (I believe about 600 showed up and debated) on what should be the "canon version" of the bible. Things that were decidedly not included were "the Gospel of Thomas" (the Gnostic Gospel), "the Gospel of Mary", and many others that were deemed non-Canon. Of note, the Book of Revelations (written by John, but not necessarily the Apostle John) was hotly contested and barely made it into the canon by a slim majority.
Either who, this has been a longer post than I intended, but all of this is to say is to consider the author and the context in which each book takes place and how they may or may not connect or contradict each other. As far as I know, the individual books and epistles are at least internally consistent. Many people don't consider these things when talking about the bible - I'm not going to get into the "mysteries of God and his ways," but for me, it makes me consider things much more carefully and has helped me, slowly but surely, learn more.
If you want a more thorough discussion I recommend Dr. Dan Wallace (textual criticism) or Mike Licona and his interviews of Lee Martin McDonald (canonicity) if you're more faith-oriented. If you're more academic or irreligious then check out Bart Ehrman.
