Can I believe in God and Evolution? This question is often provoked by a more specific one: "Do you believe in creation or in evolution?" When the issue is framed in this fashion, we are forced to choose between an apparently atheistic evolutionary worldview and a scientifically naïve creationism. Unfortunately, much of the public has accepted this framing; according to a recent international survey by the British Council and Ipsos MORI, 27% of American adults believe that it is impossible to "believe in a god and still hold the view that life on earth, including human life, evolved over time as a result of natural selection." Another 19% expressed uncertainty on the issue.
Nonetheless, according to a 1997 survey by Edward J Larson and Larry Witham, roughly 40% of American scientists are theistic evolutionists themselves! A 2009 survey by the Pew Research Center confirmed this finding, with half of the responding scientists identifying as religious and only 2% rejecting evolution.
In fact, the "creation or evolution" dichotomy is needless and false, based upon a category mistake. For example, if I held up an grapefruit and asked, "Is this fruit yellow or is it spherical?", the sentence would make no sense, because "yellow" and "spherical" are not contradictory, but complementary descriptions of the fruit.
The question "Do you believe in creation or evolution?" has the same problem. Like color and shape, "creation" and "evolution" do not occupy competing categories, but are complementary ways of looking at the universe. "Creation" is a philosophical concept: it is the belief that the universe depends for its existence upon something or some being outside itself. As a philosophical term, "creation" is an empirically untestable belief that makes no claims about how or when the world came to be, or even whether creation was a determinate "act" or an event in time. It is a philosophical tenet compatible with the theological doctrines of Judaism, Christianity, Islam, and other monotheistic religions. (A contrary and equally untestable philosophical assertion would be that the universe is uncreated, or self-subsistent.)
By contrast, "evolution" is in the scientific category. It is a statement about physical reality, not a metaphysical claim. Evolution, in its most general sense, is the inference that the universe has changed over time - that stars and galaxies and planets and living things on Earth are different now than they were in the past. In biology, evolution is the principle that all life is related through descent with modification from common ancestors. Science is the process of explaining phenomena by testing explanations against the natural world. The important element is testing, rather than accepting an explanation based on authority or personal preference. Science also restricts itself to explaining things through natural, rather than supernatural, mechanisms. Biologists cannot explain how the modern horse descended from a Hyracotherium-like ancestor by saying "God did it." They can, however, examine evidence from living as well as fossil horses and devise testable hypotheses about the relationship between them. To date, the hypotheses best supported by evidence are invariably those which agree with evolutionary theory.
Of course, religious claims that are empirically testable can come into conflict with scientific theories. For instance, young-earth creationists argue that the universe was created several thousand years ago, that all the lineages of living creatures on Earth were created in their present form (at least up to the poorly-defined level of "kind") shortly thereafter, and that these claims are supported by empirical evidence, such as the fossil record and observed stellar physics. These fact claims are clearly contradicted by mainstream paleontology, cosmology, geology and biogeography. However, the theological aspect of young-earth creationism—the assertions about the nature of God, and the reasons why that God created the universe and permitted it to develop in a particular way—cannot be addressed by science. By their nature, such claims can only be—and have been—addressed by philosophers and theologians.
The science of evolution does not make claims about God's existence or non-existence, any more than do other scientific theories such as gravitation, atomic structure, or plate tectonics. Just like gravity, the theory of evolution is compatible with theism, atheism, and agnosticism. Can someone accept evolution as the most compelling explanation for biological diversity, and also accept the idea that God works through evolution? Many religious people do.
 British Council. Press Release: Darwin survey shows international consensus on acceptance of evolution. January 7, 2009.
 Pew Research Center for the People and the Press. Public Praises Science; Scientists Fault Public, Media. July 9, 2009.