Political realism refuses to identify the moral…

““Political realism refuses to identify the moral aspirations of a particular nation with the moral laws that govern the universe. As it distinguishes between truth and opinion, so it distinguishes between truth and idolatry. All nations are tempted — and few have been able to resist the power for long — to clothe their own aspirations and action in the moral purposes of the universe. To know that nations are subject to the moral law is one thing, while to pretend to know with certainty what is good and evil in the relations among nations is quite another. There is a world of difference between the belief that all nations stand under the judgment of God, inscrutable to the human mind, and the blasphemous conviction that God is always on one's side and that what one wills oneself cannot fail to be willed by God also. The lighthearted equation between a particular nationalism and the counsels of Providence is morally indefensible, for it is that very sin of pride against which the Greek tragedians and the Biblical prophets have warned rulers and ruled. That equation is also politically pernicious, for it is liable to engender the distortion in judgment which, in the blindness of crusading frenzy, destroys nations and civilizations - in the name of moral principle, ideal, or God himself.””

— Hans J. Morgenthau