Why does Richard Dawkins think that believing in God is a delusion?

Why does Richard Dawkins think that believing in God is a
delusion?

Richard Dawkins thinks that believing in god is a delusion because, he firmly believes that religion was a mere byproduct of natural selection. he is a firm believer in natural selection, and believes that religion is not necessary to maintain social order. he also says that religion is a virus, and speaks negatively about how it spreads narrow mindedness, causing prejudice against homosexuals.