Creationism is the belief that humanity, life, the Earth, and the universe were created in their entirety by a deity or deities (typically God), whose existence is presupposed. In relation to the creation-evolution controversy the term creationism (or strict creationism) is commonly used to refer to rejection of evolution. The wide spectrum of such beliefs includes young Earth creationism holding a very literal interpretation of Genesis, while old Earth creationism accepts geological findings but rejects evolution. The term theistic evolution has been coined to refer to beliefs in creation which are compatible with scientific findings on evolution and the age of the Earth.
Creationism in the West is primarily based on Creation according to Genesis, and in its broad sense covers a wide range of beliefs and interpretations. In the 1920s in the United States the term became particularly associated with Christian fundamentalist opposition to human evolution, and several states passed laws against the teaching of evolution in public schools, as sensationally upheld in the so-called Scopes Monkey Trial. Evolution was omitted entirely from school textbooks across the United States until the 1960s. Since then, renewed efforts to introduce teaching creationism in public schools under the guise of flood geology, creation science, and intelligent design have been consistently held to contravene the constitutional separation of Church and State by a succession of legal judgements.
When scientific research produces conclusions which contradict a creationist interpretation of scripture, the strict creationist approach is either to reject the conclusions of the research, its underlying scientific theories, or its methodology. The most notable cases concern the effects of evolution on the development of living organisms, the idea of common descent, the geologic history of the Earth, the formation of the solar system, and the origin of the universe.