“… indeed miraculous. He has commenced to accomplish those things for us which we could never do by ourselves.” (Page 25, Big Book)
Sometimes people dismiss religion or spirituality as a myth or a fairy tale, using the two terms interchangeably. These are two entirely distinct categories. Fairy tales are entirely fabricated. Myths are conceptual structures invoked to explain present, demonstrable phenomena. Fairy tales are grounded in nothing. Myths are grounded in reality. You can dismiss a fairy tale. But if you dismiss a myth, you have merely eliminated the analogy. Whatever the analogy explains remains and now demands a different explanation.
What is the phenomenon in AA? Why people who were powerless have acquired power; why people who were heading for destruction suddenly change direction, without such change being consciously or deliberately activated by the person themself or by third parties. Sure, destroy a myth, but there is still a case to answer.
If there is no God (and there might not be), there is a mechanism that has godlike powers to transform an individual life in a way that is indeed miraculous. In other words: a God-like thing that is not God, an inverted tautology, something that is not itself. In other words: a logical contradiction. In other words: nonsense. Which is why I believe in God.