If any one ask, Ought we to pray for kings, from whom we obtain none of these advantages? I answer, the object of our prayer is, that, guided by the Spirit of God, they may begin to impart to us those benefits of which they formerly deprived us. It is our duty, therefore, not only to pray for those who are already worthy, but we must pray to God that he may make bad men good. We must always hold by this principle, that magistrates were appointed by God for the protection of religion, as well as of the peace and decency of society, in exactly the same manner that the earth is appointed to produce food. Accordingly, in like manner as, when we pray to God for our daily bread, we ask him to make the earth fertile by his blessing; so in those benefits of which we have already spoken, we ought to consider the ordinary means which he has appointed by his providence for bestowing them.

To this must be added, that, if we are deprived of those benefits the communication of which Paul assigns to magistrates, that is through our own fault. It is the wrath of God that renders magistrates useless to us, in the same manner that it renders the earth barren; and, therefore, we ought to pray for the removal of those chastisements which have been brought upon us by our sins.

John Calvin, on 1 Timothy 2:2, in Commentaries XXI, 52-53.