Corrolary 1: We can never prove that we are not in the Matrix.
I'm not sure we even have sufficient evidence to suggest it, let alone prove it.
Crude synopsis: if it is possible to create such an simulation then the probability that we in one is the number of possible simulated universes (v. large) vs the number of real universes (1) ie high probability that we are within a simulation.
And... everybody has the right to believe whatever he/she likes as long as the induced behavior is not harmful to others.