God has given authority over the earth to mankind. Despite man stuffing things up, God keeps his word, so he will not act on earth without getting permission from a human with legitimate authority on earth. This is an important principle.
God will not act on earth
unless a human gives him permission to act.
Jesus has defeated the enemy and given God's people authority on earth. When we pray we are not asking him to change his mind, we are giving him the authority that he needs to take action on earth.