The Bible is a unified book, and its central theme is Jesus. Although the Bible was written by different people on different continents and at different times, it still communicates one unified story, with God as the author.

If you trace the things in Scripture, the end goal of the Bible is that God was in Eden and He wants to expand around the world. But sin in some form tried to derail the plan. However, God had other plans through Jesus and the gifts of the Holy Spirit to be expressed.