By providing a naturalistic explanation of biological origins, evolution
promotes atheism. "Although atheism might have been logically tenable
before Darwin, Darwin made it possible to be an intellectually fulfilled
atheist" (Dawkins 1986, 6)..
Naturalistic explanations of origins are not necessary for atheism.
Nobody in the world can explain the origin of everything anyway.
Leaving one more thing unexplained does not much matter. Dawkins's
claim is the flip side of the "God of the Gaps" fallacy.
Naturalistic explanations of origins do not make atheism mandatory.
If God is the creator, it would make sense that he would be responsible
for creating everything, including evolution and the laws that make it
operate.
Darwin was not alone in providing naturalistic explanations. Many
people before him removed God from explanations for parts of the
universe. Pierre-Simon Laplace provided a natural explanation for the
origin and stability of the solar system. Friedrich Wöhler
synthesized urea, showing that there was no "vital" element in organic
material. David Hume argued that design was not necessary for the
origin of life. Darwin, by providing the mechanism, merely filled in
one of the last gaps. It was possible to be an intellectually
fulfilled atheist even before Darwin (Gliboff 2000).
There is nothing wrong with being an atheist if you want to be an
atheist. That some people disapprove only shows that there is
something wrong with religious bigots.
Due mainly to its being rife with intellectual dishonesty, creationism
also drives some people to atheism (Babinski 1995).
References:
Babinski, Ed. 1995. Leaving the Fold: Testimonies of Former
Fundamentalists. Buffalo, NY: Prometheus Books.
Dawkins, Richard. 1986. The Blind Watchmaker. New York: Norton.
Gliboff, S. 2000. Paley's design argument as an inference to the best
explanation, or, Dawkins' dilemma. Studies in History and Philosophy
of Biological and Biomedical Sciences 31(4): 579-597.