We can believe the Bible is inspired by God because of the Unity of Authors

There were 40 writers involved.
It was written over a span of 1600 years.
They had different educational backgrounds.
Their careers were different. Some were farmers or fishermen. Some were soldiers, others were court officials.
They came from different countries and cultures.
And each one had his own way of expressing himself, his own personality.
Because of all these differences, and especially the time difference, they couldn’t possibly get together to discuss what they were writing down. Yet they all agree in everything they wrote.
They agree on:
their record of history
their idea of what God is like
their principles for living
their view of man’s sinfulness
their prophecies of the future
How can so many writers from so many backgrounds agree in so many details?
It is because there are many writers, but one author – God himself!
2 Peter 1:20-21 says: “no prophecy in Scripture ever came from the prophet’s own understanding, or from human initiative. No, those prophets were moved by the Holy Spirit, and they spoke from God” (New International Version).
As they wrote, the Holy Spirit was with them, and helped them to write exactly the words he wanted. So Christians believe that the messages, promises and warnings in the Bible are from God himself.
The Bible is no ordinary book.
By following the instructions God gives us in it we can experience God himself,
working in our lives – changing us, helping us, guiding us.

THE MORALITY OF THE BIBLE TESTIFIES TO THE DIVINE ORIGIN

God is love (I John 4:7; John 3:16-17; Romans 5:8-9) Love is seeking the best interest of another.  God is the ultimate example.
The principle to forgive based on the forgiveness of God  (Matthew 6:14-15; 18:21-35).
The golden rule (Matthew 7:12; Matthew 22:37-41).
Humility, kindness, endurance, selflessness (1 Corinthians 13:4-7)
Universal value and equality before God of all people (Acts 10:34-35; Romans 2:11;  Galatians 3:26-29; & Acts 17:25-26).  
God’s design of marriage and the family (Genesis 2:20-24; Ephesians 5:22-34; Matthew 19:1-9;  & Ephesians 6:1-4)
The Ten Commandments (Exodus 20:1-17).
The blessings of the Lord’s Church (Ephesians 1:3-14; 1 Corinthians 12:12-13).
The hope of heaven (Hebrews 6:19-20; John 14:1-3).
Justice (Matthew 25:31-46; 2 Corinthians 5:10).  
 The Sermon on the Mount (Matthew 4:23-7:29).  
Doug Seaton

These are not placed in order of importance.