"Evolution is not a theory, it is a fact. We eat foods that are a result of forced evolution through selective breeding. Anyone who owns a poodle has direct evidence of the FACT of evolution.
The theory that is behind so much of the heartburn is of Natural Selection, where evolution results in physical characteristics of species because of the competitive advantage provided by the characteristics, as opposed to the arguments that a Creator made the universe as it is, with some arguments that the universe has been static since that act of Creation."
To define the terms:
Genotype - Genetic constitution of an individual.
Adaption - the phenomena that over the course of time, species modify their phenotypes in ways that permit them to succeed in their environment. Seen in nature in the Peppered Moth.
Phenotype - Appearance of an organism, resulting from the interaction of its genotype and its environment.
Natural Selection - Living things produce more offspring than the finite resources available to them can support, thus living things face a constant struggle for existence. The individuals in a population vary in their phenotypes. Some of this variation is inheritable; that is, it is a reflection of variations in genotype. Those variants best adapted to the conditions of their life are most likely to survive and reproduce themselves ("survival of the fittest"). To the extent that their adaptations are inheritable, they will be passed on to their offspring.
Micro vs. Macroevolution:
MICROEVOLUTION. A small amount of evolutionary change, consisting of minor alterations in gene proportions, chromosome structure, or chromosome numbers in a population. For example, (1) industrial melanism of peppered moths: the melanic form is under the control of single dominant gene that arises spontaneously by mutation from the colour gene; dark individuals are more frequent near industrial cities where light coloured lichens are rare, due to the selection force of insectivorous birds. (2) Balanced polymorphism in the sickle-cell trait: sickle-cell anaemia is caused by the abnormal haemoglobin S under the control of a single gene, lethal in the homozygous state; the trait survives because the heterozygous condition has superior fitness over both homozygotes: persons carrying haemoglobin S are more resistant to malignant tertian malaria. MACROEVOLUTION is a large amount of evolutionary change involving many elementary changes in gene proportions: the sum of many microevolutionary steps over a very large time-scale.
Fact: a verifiable statement or event that is known to have really occurred.
Theory vs. Hypothesis:
A theory is a conceptual framework that explains existing observations and predicts new ones.
A hypothesis is a working assumption, to be proved or disproved by observation and experimentation.
On to the nitpicking: Last I looked, microevolution is a fact. It's a testable, replicable, falsifiable, peer-reviewed phenomenon. It is personally observable; we've not only seen it in nature with the adaptation of the Peppered Moth to its environment, but we've used it in breeding the types of dogs and plants referred to in Random Fate's post.
Macroevolution, on the other hand, is still a theory, as defined above. We've not yet gotten a celery stalk to evolve into a poodle or a fish to become a lion. It's not testable, not replicable, and not falsifiable, and most importantly not observable, primarily because it takes millions of years to get the results. I'm not saying it's not a good theory, based on the fact of microevolution and the current fossil record, but it's still a theory.
Finally, I believe it is too simplistic to state that because evolution itself is a fact, the only remaining issue is whether or not natural selection took place, or whether the world was created "as is" by some creator. That doesn't allow for hybrid or off-the-board viewpoints. What about the person who feels the "big bang" came from God, but the whole thing's been evolving since? What about the person who doesn't believe in a creator, yet feels that the idea that this level of genetic diversity sprang spontaneously from some primordial microbe soup is a rather incredible proposition? Etc., etc., etc.
A side note based on my own observation: did you ever notice that the entire debate hinges on mutually exclusive premises? Evolutionary theory is essentially the question: 'If there was no "creator," how was the universe created, and how did it become what it is today?' Creation theory, conversely, asks: 'Given there was a Creator, how did he/she/it create the world to become what it is today?' It will never be resolved. Even if someone is willing to throw aside these mutually exclusive hypothesis and ask "How did the universe begin?", it's still not testible, replicable, observable or falsifiable.
I'm not any kind of a physicist, but I understand from friends that big bang is still being fleshed out, basically a hot or cold thing, and how did the temperature get there in the first place. We've also been revising our theories about the nature of dinosaurs, warm-blooded vs. cold-blooded. And check out this link for a synopsis of the debate between Paleontologists and molecular geneticists as to whether sufficient fossil record exists to show that modern mammals originated 65 to 75 million years ago, not 130 million years.
So why can't we just all admit we don't know exactly how the world began or why? We've got our guesses. Some are extrapolations from testable hypotheses. Others are supported by faith alone. Arguably the extrapolations should be taught in science class, but so should the drawbacks to the theories, and why couldn't the class also do an overview of world creation views through time and geographic region? The similarity of some oral religious traditions on the creation of the world, as analyzed by this paper or this excellent web page, is a truly fascinating subject: did the similarities in the stories spring from the ancient hearth of our genetic Eve, with any variations imposed only by the dimming of the collective memory over time, or are the similarities merely coincidental? Anyway, that's my really excruciating nitpick of the week.
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