i have a very hard time believing that scientists can date fossils and other finds back to "Millions of years ago" with radiocarbon dating. You can believe it is possible as for me I think that you have to be able to prove its millions of years old to start with, then you can test radiocarbon dating on it to prove radiocarbon dating is accurate.
The reason i believe evolution to be theory is because Darwin himself said it was.
Radiocarbon dating is only good for <50,000 years. Perhaps you mean "radiometric" dating, which is the general term for many different methods, incl. carbon dating. The interesting thing, is that all the methods
agree with each other. Fascinating coincidence, isn't it, if they're all invalid?
For general information on how radiometric dating actually works, try
here.
And, as I said before: of course it's a Theory. Just like the Atomic Theory of Matter and the Germ Theory of Disease.
In Science "theory" = explanation, not "supposition". Something can be extremely well-confirmed (e.g., Atomic theory of matter), but it's STILL a "theory" in the scientific sense, because it's STILL a scientific explanation.