There is one essential element that all rational moral systems must have, and that is capacity for change. Whether your conception of the good is intrinsic, as in the case of Plato’s forms or religious deities, or relative, as in the case of Aristotle’s pursuit of excellence or Nietzsche’s path to the overman, the one essential component of a moral framework must be the ability to change oneself and society, for without change no progress towards the good can ever be made – assuming, of course, that is that the current state of affairs is not the optimal one.
Viper venom contains a highly potent coagulant. Within seconds of a bite, liquid blood begins to turn solid, clotting up and blocking flow in the arteries. Religious dogmatism and political suppression of free speech are two ways of consolidating and solidifying an existing power structure by means of preventing change. Just as viper venom freezes the blood in your body, dogmatism and censorship freeze the discourse and evolution of society. If you want to get a feel for the toxicity of a political or religious agenda, look at how much it aims to prevent current or future change, how much it aims to restrain, contain and limit.