I mentioned yesterday that Darwinists have a frustrating way, in public discourse, of failing to say what they mean by evolution. Ann Coulter observes how this can function as a method of intimidation:

Just a year later, at a 2008 Republican presidential candidates’ debate, Matthews asked for a show of hands of who believed in evolution. No discussion permitted! That might allow scientific facts, rather than schoolyard taunts, to escape into the world.
Evolution is the only subject that is discussed exclusively as a “Do you believe?” question with yes-or-no answers.

In God and Evolution, Discovery Institute’s Jay Richards gives no fewer than eight meanings of the word. Commit these to memory:

Though God is the grandest and most difficult of all subjects, the meaning of the word “evolution” is actually a lot harder to nail down.
In an illuminating article called “The Meanings of Evolution,” Stephen Meyer and Michael Keas distinguished six different ways in which “evolution” is commonly used:

1. Change over time; history of nature; any sequence of events in nature.
2. Changes in the frequencies of alleles in the gene pool of a population.
3. Limited common descent: the idea that particular groups of organisms have descended from a common ancestor.
4. The mechanisms responsible for the change required to produce limited descent with modification, chiefly natural selection acting on random variations or mutations.
5. Universal common descent: the idea that all organisms have descended from a single common ancestor.
6. “Blind watchmaker” thesis: the idea that all organisms have descended from common ancestors solely through unguided, unintelligent, purposeless, material processes such as natural selection acting on random variations or mutations; that the mechanisms of natural selection, random variation and mutation, and perhaps other similarly naturalistic mechanisms, are completely sufficient to account for the appearance of design in living organisms.

Meyer and Keas provide many valuable insights in their article, but here we’re only concerned with “evolution” insofar as it’s relevant to theology.
The first meaning is uncontroversial — even trivial. The most convinced young earth creationist agrees that things change over time — that the universe has a history. Populations of animals wax and wane depending on changes in climate and the environment. At one time, certain flora and fauna prosper on the earth, but they later disappear, leaving mere impressions in the rocks to mark their existence for future generations.
Of course, “change over time” isn’t limited to biology. There’s also cosmic “evolution,” the idea that the early universe started in a hot, dense state, and over billions of years, cooled off and spread out, formed stars, galaxies, planets, and so forth. This includes the idea of cosmic nucleosynthesis, which seeks to explain the production of heavy elements (everything heavier than helium) in the universe through a process of star birth, growth, and death. These events involve change over time, but they have to do with the history of the inanimate physical universe rather than with the history of life. While this picture of cosmic evolution may contradict young earth creationism, it does not otherwise pose a theological problem. The generic idea that one form of matter gives rise, under the influence of various natural laws and processes, to other forms of matter, does not contradict theism. Surely God could directly guide such a process in innumerable ways, could set up a series of secondary natural processes that could do the job, or could do some combination of both.
In fact, virtually no one denies the truth of “evolution” in senses 1, 2, or 3. And, pretty much everyone agrees that natural selection and random mutations explain some things in biology (number 4).
What about the fifth sense of evolution, universal common ancestry? This is the claim that all organisms on earth are descended from a single common ancestor that lived sometime in the distant past. Universal common ancestry is distinct from the mechanism of change. In fact, it’s compatible with all sorts of different mechanisms or sources for change, though the most popular mechanism is the broadly Darwinian one. It’s hard to square universal common descent with some interpretations of biblical texts of course; nevertheless, it’s logically compatible with theism. If God could turn dirt into a man, or a man’s rib into a woman, then presumably he could, if he so chose, turn a bacterium into a jellyfish, or a dinosaur into a bird. Whatever its exegetical problems, an unbroken evolutionary tree of life guided and intended by God, in which every organism descends from some original organism, sounds like a logical possibility. (So there’s logical space where both intelligent design and theistic evolution overlap — even if ID and theistic evolution often describe people with different positions.)
Besides the six senses mentioned by Meyer and Keas, there is also the metaphorical sense of evolution, in which Darwinian Theory is used as a template to explain things other than nature, like the rise and fall of civilizations or sports careers. In his book The Ascent of Money, for instance, historian Niall Ferguson explains the evolution of the financial system in the West in Darwinian terms. He speaks of “mass extinction events,” survival of the fittest banks, a “Cambrian Explosion” of new financial instruments, and so forth. This way of speaking can sometimes be illuminating, even if, at times, it’s a stretch. Still, no one doubts that there are examples of the fittest surviving in biology and finance. We might have some sort of “evolution” here, but not in a theologically significant sense.
Finally, there’s evolution in the sense of “progress” or “growth.” Natural evolution has often been understood in this way, so that cosmic history is interpreted as a movement toward greater perfection, complexity, mind, or spirit. A pre-Darwinian understanding of “evolution” was the idea of a slow unfolding of something that existed in nascent form from the beginning, like an acorn eventually becoming a great oak tree. If anything, this sense of evolution tends toward theism rather than away from it, since it suggests a purposive plan. For that reason, many contemporary evolutionists (such as the late Stephen J. Gould) explicitly reject the idea that evolution is progressive, and argue instead that cosmic history is not going anywhere in particular.