Saying evolution is only a theory is exactly like saying an athlete is only a gold medal winner, or a new drug developed for some terrible disease is only a complete cure. In science, facts are the building blocks of theories. A fact would be something like "the speed of light in a vacuum is 299,792,458 m/s", or "heat travels from a hotter object to a colder one" - or even "this forum sure does attract the idiots".
At the age of five, Skagra decided emphatically that God did not exist. This revelation tends to make most people in the universe who have it react in one of two ways - with relief or with despair. Only Skagra responded to it by thinking, 'Wait a second. That means there's a situation vacant.'