Atheism, as discussed in The God Delusion, is the disbelief or lack of belief in the existence of God or gods. Dawkins advocates for atheism, arguing that it is a rational stance based on scientific evidence and reason. He challenges the societal taboo against atheism and seeks to raise consciousness about the natural world and the scientific explanations that negate the necessity of a divine creator.

Agnosticism is the view that the existence of God, the divine, or the supernatural is unknown or unknowable. Dawkins discusses agnosticism in the context of the spectrum of theistic probability, positioning it between theism and atheism. He argues that while agnosticism is intellectually respectable, he finds atheism a more rational position based on the improbability of God’s existence as suggested by scientific evidence.

The anthropic principle asserts that observations of the universe must be compatible with the intelligent life that observes it. Dawkins uses this principle to explain the apparent fine-tuning of the universe. He contrasts the anthropic principle with the idea of a divine creator, arguing that our existence in a universe capable of supporting life is a consequence of natural processes rather than a deliberate design.