In recent years the theory of evolution has been challenged by critics who contend that the scientific evidence doesn't support it. Some critics even attack the theory as a form of naturalism, the philosophical view that nature is all there is-no God, no supernatural, no transcendental order of being. The idea is that human existence can, at least in principle, be wholly explained in terms of scientific laws. Evolution, on this view, wholly accounts for human origins, in purely physical terms. Whatever the scientific evidence for evolution, a purely naturalistic formulation of the theory won't hold up philosophically or theologically, anymore than a purely naturalistic account of human nature as it exists today will.
Human beings possess spiritual souls.
That means, among other things, that we have intellects and wills, neither of which can be entirely reduced to merely natural, scientific explanations without jettisoning the reliability of all human thought and human freedom. For, as C. S. Lewis and others have argued, unless at least some of our thoughts aren't explicable wholly in terms of the physical processes of the natural world, the very scientific idea of nature itself is unreliable. For it, too, would be merely the product of biochemically determined thinking. And unless at least some of our choices aren't wholly produced by the operation of purely natural, physical laws, all our choices, including moral decisions to kill, lie, cheat or steal, would be mere products of nature. Now we all think people's thoughts or decisions are at least sometimes explicable in terms of mere physical processes.