What is needed for evolution experiments are organisms, like bacteria, that reproduce very quickly, so one can detect changes that take many generations. In my laboratory at Michigan State University, we have studied 20,000 bacterial generations in one experiment. We can observe the two essential processes of evolution in this experiment. The first is mutation, which produces genetic differences between individual organisms. The second is natural selection, by which the genetic varieties that have an advantage in the environment leave more descendants to later generations.
Scientists can only study natural forces in the material universe.
Science and religion may coexist compatibly in our lives precisely because of this essential difference. Science also depends on the internal consistency of evidence and theories, whereas religions span an enormous range of mutually incompatible beliefs. Some believe that God is embodied in nature, whereas others think God exists outside the material universe. Some believe morality evolved from within nature, whereas others contend that morals are transcendent. Some preach tolerance, whereas others claim divine support for their intolerance.