God curbs the spirit of princes, inspires awe in the kings of the earth. (76:13)
Lord Acton, “Power tends to corrupt, and absolute power corrupts absolutely.”
Powerful leaders need constant reminders that their power does not entitle them to do and take anything they want. This is the basis for a philosophical argument for a monotheistic God. Were there more than one creator/power in the universe; or if there were no power above human power, there would be no basis for asserting universal, non-relative, moral authority.
In a polytheistic system, the gods are in conflict. There is no absolute authority, and therefore no absolute right or wrong. Any position that I might take, appealing to the voice of a specific god, can be contradicted by the voice of an opposing god. The sun god dries up the water god, but the storm god blows clouds to cover up the sun god and produce more water. The sea god has no power inland, where the goddess of crop fertility reigns. And so on.
In a non-theistic system, we have to trust the human system to create systems of morality. The problem, though, is that every human created system can be modified or suspended by a person with sufficient power. The Constitution of the United States provides protection for its citizens, but Congress has passed laws abridging our rights when it feels that it is necessary.
A monotheistic system has a God at the top of the system whose authority (in theory, and usually in practice) cannot be altered by human beings. It’s answer to Lord Acton is that since human power is limited by God, then a human leader who is curbed by a belief in God and held in awe of God will never be corrupted, and certainly never be corrupted absolutely.