My brain always goes meta when people attack evolution as "just a theory." I start to think to myself - "Well, you don't understand... New theories are formed

My brain always goes meta when people attack evolution as "just a theory." I start to think to myself - "Well, you don't understand... New theories are formed all of the time, but the ones that are the most fit survive..." And then I realize I'm practically using evolution to explain what a scientific theory is, so that the person can understand that evolution is not "just a theory." D'oh!