This is the second half from my reply to Dale. This way, nobody has to go through the first part of my beliefs.
Theory: The scientific meaning of this word is not the same as the colloquial or lay man's definition. In science a theory is a complete body of knowledge. A theory becomes a theory when all available evidence suggests that it is probably the case. If a single piece of evidence comes up, the theory must either be refined or thrown out.
A scientific theory does two things:
i. Accounts for and explains all available evidence.
ii. Makes predictions as to what we can expect to find in the related field.
Peer-reviewed publishing- This is the process by which new knowledge is added to the scientific consensus. A scientist does an experiment, builds a conclusion and goes to other experts in the field. Regardless of whether or not the other experts agree, they poke holes in the research. The pull in every which way to ensure that his or her findings are indeed accurate. There are extremely high standards that must be met when things are accepted as science.
So now we have that out of the way.
The 'evolution' part of the 'theory of evolution' is also tricky for some people****. Evolution is observed. It happens. We have known that it happens since before Darwin. What he contributed was the mechanisms behind the observation. The theory, as a body of knowledge, explains the observation (which is the data) through natural selection, sexual selection, punctuated equilibrium, drift, etc. So when we refer to the theory of evolution, we are referring to the knowledge that describes the process of how organisms evolve.
****Evolution does not deal with the origin of life on earth; that field of study is abiogenesis.
There are millions of peer reviewed articles that support evolution. Millions. The theory is one of the most solidified that we have. (For many in depth examples, with citations click here.)
So why don't I buy into creationism?
1. It does not explain anything or tell us anything about the natural world. With science you gather all the facts, the evidence, and you make a conclusion. With creationism/ intelligent design, you start out with your conclusion and then announce all contradicting facts are wrong. For example; If God made us in present form, why do we have complete fossil records for the evolution of modern species? Why do humans share 95% of DNA with chimpanzees? Why does all the evidence indicate common ancestry?
There are no pieces of evidence that point us in the direction that life on earth was designed in the modern form. Creationism/ ID merely asserts that something is the case without doing the research to back it up.
With real science, you are constantly trying to overturn the accepted theory with every experiment you create; you are testing it. You want to blow a hole in it. Creationists, on the other hand, frantically try to protect their brittle impostor of science; they never try to disprove themselves. They say they have the evidence; but nothing is stopping them from publishing their findings in scientific journals and overthrowing modern biology.
2. It makes no predictions. (Remember a theory not only explains what we have, but it tells us what we should expect to find.) The reason our live spans have increased so much is because of modern medicine, which is based on evolutionary theory. Darwin wasn't able to see things on the molecular/ cellular level, but he predicted that there would be molecules of inheritance. With the discovery of DNA in the mid 20th century, we know exactly what the molecules of inheritance are, and how they work.
Intelligent design doesn't have that. There are no predictions made by this idea. It cannot tell us what we expect to find. It cannot tell us how to treat disease. But germ theory (based off of the theory of evolution) can. It cannot tell us what would happen if we tampered with a specific gene; because it denies that these structures are what shapes us, physically.