Skepticism is the best of the isms. It is critical thinking, it is science (the scientific method), and vise versa. Question everything, doubt what you're told, look for the other side of the story, or as Ronald Reagan put the Russian proverb, "doveryai no proveryai" (Trust but verify). If someone is not skeptical of what they are told, and won't question or consider facts that don't support their view, that doesn't make them a bad person: but they're not a practicing person of science, logic, reason or critical thinking. If they can't accept their biases or that truth, then they're not a self-aware person.