First, I want to deal with the idea that one either 'believes' that evolution is true, or 'believes' that it is not. The term 'belief' implies faith, and there is no faith involved when one accepts a scientific proposition. Either the evidence supports it, and we hold it to be true, or the evidence does not, and we hold it to be false. All the while, of course, understanding that a new evidence comes in, our original position will most likely need to change.
|The Tree of Life|
On the contrary, I have noticed that folks who don't think evolution is a correct theory tend not to be so skeptical or scientific in their views. They go into their study of the theory knowing which outcome they plan to draw, which is quite the antithesis of good thinking.
Evolution, both microevolution and macroevolution, are well-documented and supported by (literally) billions of individual pieces of mutually-buttressing evidence. They are elegant and simple explanations that account for life in its amazing splendor, but they are unfortunately often misunderstood or misrepresented (in particular by those who feel they have a theological reason for disbelieving in them).
One of the more common misconceptions that I've run into is that evolution by natural selection means that life came from non-life. It doesn't. All evolution by natural selection describes is what happened to that life after it got started. The life-from-non-life phenomenon is described by the theories of abiogensis.
Another misconception about evolution is that it implies that the universe had no creator. Evolution has nothing to do with cosmology; there are a myriad of cosmological theories, some consistent with a creator, some not.
Also, despite what creationist in particular wish to say, evolution has nothing to do with luck. There is often a straw man argument put out claiming that evolution must be wrong because the statistical odds of a, for instance, human randomly coming to be is akin to a tornado blowing through a junk yard and assembling a 747. Now, they're right in saying that such a thing spontaneously happening is ludicrously improbable. However, evolution is driven by natural selection, which is the opposite of luck, and mutations in the genetic code, which happen quite frequently thanks both to shoddy biochemistry and radiation from cosmic sources. When you add together all of the individual probabilities along the way with this in mind, we see that such an occurrence isn't unlikely at all.
I like the way that Richard Dawkins put it- life is the result of non random selection of randomly varying replicators.
Or, some Darwin for you: there is a grandeur in this view of life.
Nor is the current understanding of the theory 100% accurate. No theory is 100% accurate, because we do not know 100% of the evidence (and never will). The best we can do is eliminate the biases and errors that we find, and continue to refine our scientific best-guess. That doesn't make the theory wrong, just imperfect (like every other theory). When folks try to claim that one piece of evidence (which they, of course, are privy to) totally disproves the theory of evolution (usually with the addition: 'and therefore creation theory is correct), they clearly fail to understand the scientific process as detailed above.
I have likewise seen claims that the laws of thermodynamics, entropy in particular, to discredit the theory of evolution. Using the second law of thermodynamics in attempt to discredit evolution is, pulling no punches, daft. Entropy applies to closed systems, which the earth (with its constant influx of energy from the sun and release of energy through various processes) is quite simply not. Furthermore, the constituent organisms themselves are not closed systems either. Put simply, entropy has no deleterious effect on macroevolution.
In the end, I think anybody who approaches the theory of evolution by natural selection with a skeptical, critical, unbiased mind will find that it fits all the evidence, that it has tremendous explanatory power, and that it isn't this kid-corrupting evil that some folks seem to think that it is.
It is a truly remarkable achievement of the human mind, and it allows us to see the world in all of its true glory and splendor in a way that simply shrugging one's shoulders and appealing to divine authority just simply doesn't permit. I'm awestruck at the variety, complexity, and cooperation of life here on Earth.
When you understand how it all took place, it is even more beautiful.