One should always be open to the possibility that a pet theory can be falsified, but doubting some form of evolution and the big bang theory is probably irrational at this point. Quite simply, there are no better explanations for the universe and the diversity of life on earth. If you doubt some form of evolution, then you will have your work cut out for you to find a better theory. An alternative theory will have to explain geological and biological data at least as well as evolution without falling prey to falsifying data. It'll also have to make non-trivial predictions about future geological and biological observations. If you're determined to doubt something you can certainly do better than doubting evolution and big bang theories.