Evolution is a scientific theory describing change in allele frequency over time. This accounts for the diversity of life on earth, starting from a common ancestor by the processes of evolution driven by natural selection. The theory was proposed in Charles Darwin's book The Origin of Species and since developed to include genetics and many other scientific discoveries.
Evolution is often linked to atheism because it is perceived to be a threat to biblical literalism and young earth creationism. However, many religions and churches accept or at least tolerate evolutionary theory. 
Evidence for Evolution
An in-depth study on the subject of evolution is beyond the scope of this wiki. Only those arguments that relate directly to atheism and the existence of God should be cited in articles. For more information, please visit any or all of the following:
- TalkOrigins website
- Evolution Wiki
- "Evidence of Common Descent" at Wikipedia
- "List of Transitional Fossils" at Wikipedia
- "Human Evolution" at Wikipedia
Common Misconceptions about Evolution
There are some very common and persistent misconceptions about the basics of evolution itself:
- Evolution only concerns itself with the diversification of living species. It does not address other topics such as the origin of life itself, the Big Bang, the formation of planet Earth, and so on. These are each covered by different scientific fields of study, such as abiogenesis, cosmology, and physics. Creationists often misuse the term "evolution" to erroneously refer to pretty much any science that contradicts a literal interpretation of the Book of Genesis (see the Jack Chick tract 'Big Daddy' for an example).
- Evolution is both an established fact and a scientific theory. In science, a theory is not the same thing as a hypothesis. Those who try to dismiss evolution with the claim that it is "just a theory", are ignorant of the meaning of the word "theory" as it's used in science.
- Micro-evolution and macro-evolution are not distinct processes.   Small changes can accumulate over long periods and results in large changes.
- Evolution does not predict that speciation will result in a completely different kind of animal.  Evolution predicts mammals remain mammals and primates remain primates, etc. Generally, evolution does not allow for two different species to interbreed (i.e. a Crocoduck cannot occur).
There are many other objections made against evolution but these are addressed in the resources cited below. The TalkOrigins archive is an excellent and comprehensive resource regarding objections to evolution. 
Religious Objections to Evolution
- The grouping of life specified in the bible is called a "kind" and has fixed boundaries. This is not consistent with the current scientific consensus on the common descent of life. The Bible does not define the boundary of a kind.  The study of kinds, as described in the Bible, is known as Baraminology and is a form of pseudoscience.
- There is insufficient time for evolution to take place if young earth creationism is true. Youth Earth creationism considers the Earth to be less than 10,000 years old. Evolution would require a longer time period to evolve complex life from the common ancestor: probably hundreds of millions to billions of years.
- Humans are descended from other animals. If animals do not have souls, at what stage did human ancestors acquire a soul? The idea of common descent is therefore objectionable.
However, being an atheist is not a requirement for understanding and accepting evolution. There are plenty of theists who see no personal religious conflict in accepting evolution and believing in a deity.  Evolution is a biological science and does not say anything about deities, one way or another. Likewise, not believing in a deity does not automatically mean that one accepts evolution; for example there are non-theistic groups such as the Raelians who deny evolution.
Theistic evolution is a group of beliefs relating to the compatibility of religion and evolution. They range from God creating the laws of nature with the knowledge that they would result in humans to the belief that God directly influenced the mutations that occurred to produce humans. Many religions accept evolution but consider abiogenesis to have a supernatural cause.
While claiming compatibility with science, theistic evolution is not required for the evolutionary process to occur and does not provide any additional explanatory power. Therefore the theistic evolution hypothesis can be discarded by Occam's razor.
Evolutionary processes are wasteful and unnecessary
- Main Article: Argument from poor design
Evolution is full of failed attempts, suffering of living things and the extinction of most historic species. An omnipotent designer would not use such cruel means to create humans.
- ↑ 1.0 1.1 Acceptance of evolution by religious groups, Wikipedia 
- ↑ John D. Morris, "What Is The Difference Between Macroevolution And Microevolution?" 1996, Acts & Facts. 25 (10). 
- ↑ Douglas Futuyma, "Evolutionary Biology" (1998), pp.477-8
- ↑ Watch Tower Society, "Was Life Created?", p. 20
- ↑ Index to Creationist Claims, TalkOrigins archive
- ↑ Watch Tower Society, "Was Life Created?", p. 28
- Warren Kurt VonRoeschlaub, God and Evolution, TalkOrigins archive.