What is the central theme or message of the Bible?

The Kingdom (or Government) of God. How this earth will be turned into a Paradise, the way it was originally purposed to be done. Most importantly, God, the Universal Sovereign, will have his name sanctified!

The central theme of the Bible is based on what Jesus said in Matthew 6:10 which states “Let your Kingdom come.” Through this real heavenly government God promises to restore what was lost, perfect eternal life in paradise earth. Thus the overall theme is the vindication of God’s right to rule humankind by means of his heavenly Kingdom.

Man's fall from grace with God and reconciliation through Jesus Christ.

The central theme of the Bible is the vindication and the sanctification of His name. Also, it is the vindication of his right to rule (His Sovereignty) by means of his Kingdom in the hands of His son Jesus Christ.

Obey or die.

Love

The Bible shows you of your sin and the only Saviour from sin.

...that authoritatian tyrants have an inherent right to abuse anyone they please.

Death

The Bible is a diverse collection of thoughts that often don't mesh. It's hard to know if there is an actual central theme. It's basically, plotless.