You appear to doubt the authenticity of the Bible. The only part where they may have been written in retrospect is the Pantateuch, or Torah which is the first five books of the Old Testament. The original books were destroyed in 583 BC by King Nebuchadnezzar I of Babylonia when he burned down the Temple in Jerusalem, and the scribe Ezra, was the editor of the rewritten version in the 5th century BC. All the books from Joshua onwards are original.
Many prophesies were about the coming of Christ and were written from 500 BC and for several centuries before His birth. One of them even told of Him coming as a baby, gave Him his name, where He would be born and mentioned the gifts He would get. What more do you want?
It has been calculated that over 600 prophecies have been shown to have been fulfilled and many have yet to be fulfilled. One of the great prophet, Jeremiah gave one which was partly fulfilled. The first part happened, but the second part did not. In Jeremiah 46.20, written 630-580 BC, the prophet says that Nebuchadnezzar will come from the north and sweep through Egypt, destroying it.
According to a clay tablet in the British Museum the Babylonian King and his army did indeed come to the delta in Egypt but but as there is no historical record of any campaign he must have departed without attacking it. They had fought at Carchemish and Egypt had lost, so there is a theory that He actually came with his daughter. They both sailed with her retinue southwards, thus fulfilling the prophecy over the direction, but at Thebes the Princess married the Pharaoh to cement a peace treaty between the two countries. After that the Babylonian King sailed north to rejoin his army and went back home.
My Egyptology and ancient history studies.