I didn't say that just because it exists it's true. There are 2 main reasons: 1 is the fact that over 400 years, individual books were written by people of various ages, occupations, and social classes, yet the theme is consistent throughout. The second (and more important) reason is the Bible's prophecies. There were many small prophecies written by someone that became part of the OT which were later recognized and pointed out by people writing the NT, not to mention Revelations, which is coming true currently. I do appreciate that you're at least sort of open to faith though.