Its more complex then that. Humans have biases, and the things we believe we often shield from the same level of scrutiny we apply to the beliefs of others. We are far more likely to find faults in the beliefs of others, while missing those same faults in our own beliefs. Such as those who claim religion to be true but other equally unproven theories to be false. They will scrutinize those other theories with a fine tooth comb, while remaining ignorant to the fact that their own religious beliefs succumb to the same flaws they dismiss other theories for.