It is not true that there is no evidence, just that it is fake evidence. There are two common fallacies at work at least, which provide fake evidence, the first being tradition, and the second "ad populum".
In other words the belief that if it is old it must be true, and the belief that, if a lot of people believe it it must be true. Neither are any better than believing, that if the sky fairy said it, it must be true.