If I understand you correctly your confused why people would believe a book that was written by humans, in some cases along time after Jesus death. My humble opinion is the bible claims many supernatural occurrences, including bringing people back to life. Simple answer: if you choose to believe the bible you are believing in a lot of supernatural power. It's not a stretch at all for the bible to claim the authors were inspired by God, I mean look at what else it claims. You either believe it or not. Your question is a good question however. If you really are curious about ancient text the history channel has done multiple documentaries on the bible and other writings, very informative.