Not stupid, just misinformed. Many people think the theory of evolution actually means the hypothesis of evolution. They also don't understand that theory doesn't necessarily mean "this is what we think happened". Medicine is all theory too, because this type of theory ("accepted theory" as it's referred to in the scientific community) is a collection of observations, evidence, laws, data, repeatable tests etc.

The 6,000-10,000 year old Earth belief also runs into problems with continental drift. You can't possibly tell me that Africa and South America split apart and drifted all that way in such a short amount of time. Yet, there are known fossils that exist only in small areas of a coastal tip of Africa and South America, and those small pieces fit together perfectly.