I think Wretchard of The Belmont Club hits it out of the park on this one:
Now after Obama built up a big delegate lead on Hillary, the Democratic Party was essentially committed to carrying Obama whether or not Hillary found some way to overtake the lead. Remember, Obama once in the lead, is always in the lead. Otherwise it’s a lynching. I think Wright is essentially running up the Jolly Roger knowing full well that the Democratic Party will have sail under those colors or lose the black vote. He’s going to force the Democrats to take Obama on his terms. This is the revolutionary act. Wright believes he has an historic opportunity and he’s going to take it.
I think part of the messianic air about Obama was that somewhere in the national consciousness people saw him as absolution for America’s original sin. In a sense, he literally was a messiah, come to forgive America for the sin of slavery and racism. Someone who could lead us into the promised land of post-racial politics. Reverend Wright, a man who built a ministry on racial politics, will apparently have none of that. Obama is now a false messiah.