In the modern day and age it's more important than ever to separate fact from fiction. There are some truths that are absolute and no matter what anyone says they cannot be refuted. Generally we regard such concepts as scientific fact.
Progress is built and operates on irrefutable facts. The environment around you whether artificial or natural have these in common. Airplanes fly because the lift under the wing is greater than the gravitational force on the airplane. The same concept is found in nature with birds. The boiling point of water is always 100 degrees centigrade whether anyone believes in it or not. There may be thousands of ways to design the wing and boil water however the outcome must satisfy certain conditions for it to work. Truth doesn't require belief, truth always has the highest leverage. It proves itself time and time again and doesn't need anyone's approval.
Then there are things which change consistently. Things like politics, and religion, The words used to describe these abstract ideas are belief, faith, or opinions. Whether any given political party is good or not good, is subject to perspective and opinions. There is nothing wrong with these fluid concepts. We do not need to have cold hard irrefutable facts for everything we come across to make progress. However we often have to make decisions as a society based on the best approximation, which is why it's generally important to find a way to deal with these fluid concepts. In mathematics we have concepts like linear algebra, probability and vector calculus for dealing with things we do not truly know to be true. This is what machine learning is all about. Machine learning uses empirical evidence (data) and applies the concepts above to reach an 'approximation' of the truth.
Given that these concepts and ideas are fluid and can change there are generally forces that will attempt to persuade you to believe in a given narrative. The news media trying to persuade the crowd on a public figure as an example. All these things are great and one could argue that in general having diverse perspectives on thing is generally a good thing for society.
What I believe is detrimental to mankind is the concept of absolutism for any fluid concepts. I label this as 'thought cornering', an example of this is mandating a law that makes the crowd think / say certain things about political figure or religion. Being born into a household of a given religion, and being forced to only practice one religion is another example of such 'thought cornering'. Objectively speaking, no one can say the religion they're born in is the 'best'. You can identify with a given religion because it's the most 'convenient' but saying it's the 'best' is an undoubtedly untrue statement due to the nature of the circumstances.
Concepts like politics, religion that are fluid and are bound to change based on perspective, can never truly have the same attribute as scientific fact because it changes constantly. I believe it's important to recognize that anytime you experience thought cornering, where the choice is taken away by force it's often better to balance out by inserting some skepticism and be biased to the opposite of the statement being enforced, while at the same time being open for further empirical evidence to skew you back. If no further evidence is given your opinion is most likely to be correct.
It's important to understand the distinction between fluid beliefs and irrefutable facts. They have completely different properties and serve different purposes. Enabling fluid belief for concepts that are irrefutable is detrimental to any society or individual. After all progress requires constants. Can you imagine if we lived in a world where the force of gravity, or boiling point of water changes every second of everyday. We could never build anything. Figuring out truths that don't change so they can be used as the foundation of growth and development is necessary for society to progress. Debating things that are irrefutable is detrimental to any society.