This YouTube character makes some interesting points on the Westboro Baptist Church and the Christian Religion. Warning the language is not scholarly but rather more like what you hear in a Kevin Smith movie. And let me stress, I don't support his uncivil verbal attacks on "Christians"; I just want to play this clip to explore the kernel of truth in his argument: That the Westboro Baptist Church read, follow and faithfully cite the same Bible as all other fundamentalists. Those evangelicals who argue that the WBC do not know their Bibles or are citing things that aren't in the Bible are utterly deluding themselves. Period. They just adopt for the most mean spirited "literal" interpretation of the Bible as possible. They are well within the tradition of 5-points Calvinism. But again, they just opt for the meanest interpretation of 5-points Calvinism possible.
21st century Western societies are much nicer places than 16th Century Europe when Calvin operated. So mainstream Calvinists today, though they can sound mean, still tend to draw a line of civility that reflects 21st century thought and tend not so sound as mean as Calvin did in the 16th Century. It's the Phelps' that cross that line. Indeed Calvin had Michael Servetus burned at the stake for publicly denying the Trinity! You don't get any meaner than that.
Indeed, in researching Calvin on Romans 13, I've found he said some mean things that no 21st Century mainstream Calvinist would cite, such that I thought I was listening to Fred Phelps. But in reality, it's Phelps in all of his mean spirited glory who sounds like Calvin. For instance, one reason why Calvin held it's sinful to rebel against political tyrants is that God may have sent a tyrannical King to punish a people!
From his Institutes of the Christian Religion, Book IV:
25. The wicked ruler a judgment of God
But it we have respect to the word of God, it will lead us farther, and make us subject not only to the authority of those princes who honestly and faithfully perform their duty toward us, but all princes, by whatever means they have so become, although there is nothing they less perform than the duty of princes. For though the Lord declares that ruler to maintain our safety is the highest gift of his beneficence, and prescribes to rulers themselves their proper sphere, he at the same time declares, that of whatever description they may be, they derive their power from none but him. Those, indeed, who rule for the public good, are true examples and specimens of big beneficence, while those who domineer unjustly and tyrannically are raised up by him to punish the people for their iniquity. Still all alike possess that sacred majesty with which he has invested lawful power.
I will not proceed further without subjoining some distinct passages to this effect. 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.
There Calvin explains not only why something like the American Revolution -- which would happen a few hundred years later -- would be sinful, but answers the question: Why do bad things happen to good people? As Calvinist, the late D. James Kennedy used to put it, "they don't, because there are no good people." So if a bad thing happens to you like a burglary, murder or other personal tragedy, it's God cursing man. Likewise, if a Saddam Hussein rose to power in America, political rebellion would be sinful because the tyrant is God's punishment on America. You should now be able to see how the Phelps family are well within the tradition of 5-points Calvinism in thanking God for all of these terrible things that happen like 9-11 and Katrina.