Now consider the probability that human beings made a fatal error in constructing the big bang theory. This number may be extremely small, but it is a gazillion times bigger than the former number!
The more likely possibility is that human beings made an error. Thus it is more rational to believe in the possibility with the greater probability, namely that human beings made a fatal error in constructing the big bang theory.
Welcome to David Hume's argument against miracles! It is valid.