God's Debris espouses a philosophy based on the idea that the simplest explanation tends to be the best. It proposes a form of pandeism and monism, postulating that an omnipotent god annihilated himself in the Big Bang, because an omniscient entity would already know everything possible except his own lack of existence, and exists now as the smallest units of matter and the law of probability, or "God's debris".
The central character, according to the introduction, knows "everything. Literally everything." Adams, whose knowledge is as incomplete as the next person, got around this by using the aforementioned "simplest explanation" for each concept raised in the book because, while "in this complicated world the simplest explanation is usually dead wrong", a more simple explanation often sounds more right and more convincing than anything complex.
This character, the Avatar, defines God as primordial matter (like quarks and leptons) and the law of probability. He offers recommendations on everything from an alternative theory for planetary motion to successful recipes for relationships under his system. He proposes that God is currently reassembling himself through the continuing formation of a collective intelligence in the form of the human race, modern examples of which include the development of the internet; this is related to the idea of the Omega Point.