Evolutionists tend to believe and accept some form of the Darwinian argument that a natural selection process and environmental factors are responsible for all the forms of life on Earth. Life, as it exists today for evolutionists, is a result of a series of random cosmic events that caused chemical processes to create life-forms. All life-forms on Earth are related from the most minuscule to the most complex.
Darwin's view of evolution heavily favors natural selection — or "survival of the fittest." Natural selection favors genetic variations that will most likely give the species the best advantage at surviving.
Evolutionists are often divided into two groups: punctualists and gradualists. Punctualists believe life developed sporadically in short bursts as a result of environmental changes. In contrast, gradualists believe life developed slowly and gradually, over longer periods of time.
Darwin's theory of evolution belongs to the gradualist camp. He believed evolution to be a slow, gradual process with slight variations over time due to natural selection.
In addition to these distinctions regarding evolutionists, there are also theistic evolutionists as opposed to the more common atheistic evolutionists. Theistic evolutionists merge two views — creationism and evolutionism. On the other hand, atheistic or traditional evolutionists maintain more of a Darwinian view of the process.