To rule is to take responsibility for the welfare of the people. The ruler’s task is to administer justice without fear or favour, as one placed above the people who represents the law of God and is ultimately accountable to him.
Likewise, God’s people keep themselves unpolluted and sober-minded, free from all sin, for the sake of a lost world to which they witness. Their calling is much higher than that of an earthly king, for the consequences of their prayers and their testimony is far more long lasting and more momentous than any rulings or decisions made by an earthly king. They are indeed kings and priests to God.