It’s hard to believe that you were ever mistaken. 😏 However the cult of Mohammed is based of the belief that he and his followers were entitled to steal from others and murder them for their wealth. A Marxist on the left who believes that all property is theft justifies his own theft and murder of the bourgeoisie on that basis. A civilization of sorts can exist and even thrive if if it believes it is entitled to steal from others and that the leadership has a right, divine or otherwise, to steal from the plebes.
Is murder always wrong? A Brutus , Cromwell or a Rousseau would disagree. And consider the dilemma of a trolley problem where inaction is worse than action. It’s sometimes simple, sometimes not.
Is democracy universal and inevitable? While I would hope so the evidence is against it. I suspect that your optimism is based on utilitarianism, that freedom provides that maximum good for the most people. What operates against that is the tragedy of the commons and the idealism of those, religious or secular, who believe that they alone know the wisdom of Mao or Allah. At heart I am a pluralist but I realize that not everyone shares this as an ideal.