If the Creator wanted a great oak in a certain place at a certain time, He would not have to wait until that time comes, and then get someone to dig up a big tree and transplant it. But hundreds or even thousands of years before, He could cause an acorn to be dropped in the right place and the tree would be growing there healthy and strong at the appointed time. 

If God wanted a certain message to be given to a certain people at a certain time. He would not have to wait until that time to get someone to write the message and try to get it into circulation. Instead, He could cause the message to be written thousands of years in advance and have it in worlwide circulation, in all languages, when the time comes.

Through prophecy, the Bible authenticates that it alone transcends time and space. No other book dares to establish its credibility by telling the future in advance.