There are 2 books in the The Avatar series. The newest book is The Religion War which came out in 2004.

1
God's Debris

Book cover of God's Debris
Explore the mysteries and magic of the cosmos with the acclaimed creator of Dilbert. 

God's Debris is the first non-Dilbert, non-humor book by best-selling author Scott Adams. Adams describes God's Debris as a thought experiment wrapped in a story. It's designed to make your brain spin around inside your skull.…
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2
The Religion War

Book cover of The Religion War
In this frenetically paced sequel to Adams' best-selling "thought experiment," God's Debris, the smartest man in the world is on a mission to stop a cataclysmic war between Christian and Muslim forces and save civilization. The brilliantly crafted, thought-provoking fable raises questions about the nature of reality and just where…