Competence normally means ability to function within a system that includes other people and the natural world.
If you suspect that beliefs you have been taught are false, then what do you do? You might be right in your suspicion, but you might yourself have false beliefs that you acquired without paying much attention to them and without realizing that there could be anything controversial about them.
Furthermore, a conflict of beliefs might eventually help the community when the community revises its beliefs, but at least in the short term and often in the long term, if a minority group (possibly only one person) proposes an alternative belief in conflict with prevailing beliefs, then the minority group usually gains nothing. Almost all of human evolution took place before human beings had written language, so using a pen name (such as Mark Twain, Doctor Esperanto, or George Orwell) wasn't an option.
Isn't it unusual for one person in some community to pass on his or her genes, and for all the other members of the community to fail to pass on their genes because they had some particular false belief? If most of a community has a false belief, then I'm wondering how recent the belief is. The human beings who are members of the community descended without break from a long line stretching all the way back to single-celled organisms. No past false belief prevented their ancestors from reproducing. Is the false belief something very new, or did conditions in the world suddenly change to make a belief that was true no longer true?