Definition
Atheism is the absence of belief in any god or gods. The term is used in two related senses. In a broad sense it names a simple lack of theistic belief — the state of not affirming that a deity exists. In a narrower sense it names a positive position: the considered judgment that no god exists. Both usages are current, and disputes about atheism often turn on which one a speaker has in mind.
Atheism is not itself a worldview, a creed, or a moral system; it is a single answer to a single question. People arrive at it from many directions — philosophical argument, scientific naturalism, personal experience, or simply never having been raised in a religious tradition.
Why it matters
How it works
Because atheism is defined negatively — by what it does not affirm — atheists differ widely in their reasons. Some argue that the available evidence weighs against any deity; others hold that the concept of God is incoherent; others simply find no compelling reason to adopt the belief in the first place. Dawkins uses a seven-point scale to capture these gradations, placing himself near, but not at, the "strong atheist" end, since strict certainty would itself overreach the evidence.