It took about 1500 years for the whole Bible to be written - from Genesis, written at the time of Moses, to Revelation, written by the apostle John about 65 years after Christ's ascension. There were many different authors, living at different times and in different places. God guided them so that they wrote in their own words what he wanted them to say. This means that the Bible is a completely dependable and trustworthy book. We can believe everything it says.