Calvin on honoring leaders

We, in certain Christian circles, tend to bash Obama. However, I read in Calvin on how we should honor and reverence the office. We must honor the man because God placed him in office. Obama is God's minister. We may vote President Obama out in the fall for his policies, but we must not disparage him. Here's a quote by Calvin:

We need not labour to prove that an impious king is a mark of the Lord’s anger, since I presume no one will deny it, and that this is not less true of a king than of a robber who plunders your goods, an adulterer who defiles your bed, and an assassin who aims at your life, since all such calamities are classed by Scripture among the curses of God. But let us insist at greater length in proving what does not so easily fall in with the views of men, that even an individual of the worst character, one most unworthy of all honour, if invested with public authority, receives that illustrious divine power which the Lord has by his word devolved on the ministers of his justice and judgment, and that, accordingly, in so far as public obedience is concerned, he is to be held in the same honour and reverence as the best of kings. (Calvin Institutes Book 4, Chapter 20, Section 25),