I think you might be trying to assert an objective moral law --- you could assert this as a Kantian or follow the natural law tradition discoverable in Aquinas among others. I have a fair amount of sympathy for the natural law thesis, though there's no doubt that even if one grants it exists, it is not immediately self-evident and requires certain prerequisite beliefs as a foundation for it's rationality. (Granted, there are no ethics without at least an implicit metaphysics and first principles are not demonstrable, though one can intuit them.) C. S. Lewis wrote a book decades ago, The Abolition of Man, that argued for a perduring sense of morality transcendent of any particular culture. I think one can become so deracinated and cut off from communal relations that foundational experiences necessary to recognize an objective moral law are lacking. And, of course, in a meritricious, decadent society, sophists gain control of the modes of education and youth begin ignorant and end in entrenched ideology that blinds them to any substantial understanding of reality. Truth as transcendent purchase on an objectivity that cannot simply be written out of existence by human fiat is pretty much the opposite of cancel "culture."