Evolution by Natural Selection
Paley's 'happy' natural world was not one that Darwin recognized. Although he was strongly influenced by Paley's exquisite description of the complexity of systems in the natural world, he took even more from Malthus, whom he described as 'that great philosopher'. For Darwin, life on Earth developed vigorously and dynamically over time, and was characterized by death, suffering and extinction. There was nothing edifying in the way that an ichneumon wasp paralysed caterpillars to provide food for its eggs, and there was no sign of a rational or benevolent Creator. However, the world and its parts were no less magnificent or well designed for all that. Indeed the great wonder of life was that, without any grand designer, it seemed to find complex and often brilliant solutions to problems posed by changes in the environment as well as by other factors, such as competition within and between species.
According to Darwin and his followers, either because of changes in the environment, or because of competition among or between species, certain members of that species are much more likely to survive than others. In certain situations some variations, such as a longer beak for a bird, gives that organism an advantage over its competitors, so what was originally a chance and perhaps rare variation becomes commonplace. These individuals are now much more likely to breed with each other and to reproduce offspring with similar characteristics to themselves. In such conditions, the species 'adapts' itself to the new situation. If this process continues for a sufficiently long time, and groups within a species become isolated from each other, or are unable to breed with each other, a new species develops.
Belief in evolution, or evolution by natural selection, by no means precludes belief in a deity, or in the God of the monotheistic (Judaism, Christianity, Islam) religions. Many scientists remain deeply religious while believing in the Darwinian account. Most of the evolutionists who immediately followed Darwin did not believe in evolution by natural selection. Why not? Well, one of the key features of Darwin's idea was that evolution occurred by chance. Many evolutionists, Darwin included, felt that Evolution could well be working towards increased complexity, if not a divinely pre-ordained goal. It is in this context that we might begin to understand how many Christians can believe quite happily in evolution as a mechanism set in motion by God.