On what would have been his 80th birthday, Martin Luther King Jr. must be smiling from whatever heavenly vista he was rewarded for giving his life for black justice and American freedom. Forty years after King was gunned down in Memphis, Barack Obama rode the promise of change into the White House. It’s as if Malcolm X’s choice of the ballot or the bullet as the means to revolution has now been resolved into a seamless juxtaposition that bookends our modern struggle for black progress. King’s bullet, Obama’s ballot: These paraphernalia of fate symbolize our tragedy and triumph; they capture Moses dying and Joshua rising. In many ways, such a story rings true. The millions of T-shirts with images of King and Obama steamed side-by-side were hawked by street vendors even before Obama claimed the presidential nomination of the Democratic Party. King's appearance on the chests of millions salutes his iconic status as arguably the greatest American we've seen, and surely as the Great Black Man. His words are the measure of our deep yearning to live free of the weight of race; his heroic action is the engine of our protest and survival. King's blood mixed with American soil and from it sprouted new life, new possibilities and a new future. Obama sprang from King's sacrifice. Without the bullet King took, Obama may have never secured a place on the ballot. Obama cut his rhetorical teeth on King's eloquence, fashioning his words to reflect the gravity of King's moral universe. Since Obama didn't grow up in a traditional black American home, he worked hard to appreciate the logic and emotion of black existence. King's words—and those of preachers in the black church—were the touchstone of Obama's eager embrace of the complicated roots from which he drank. Like King's martyrdom, Obama's presidency is a talisman of racial possibility, a sign of what may spring from an event whose meaning continues to grow. Both King and Obama charted unlikely paths to cultural and political power: King as a young preacher thrust into international fame as he combated the forces of hate, Obama as a former community organizer who seized the reins of power because that hate had been largely defeated. But if King and Obama mirror each other as twins of destiny, their divergent roles shatter easy assumptions of their common vocation. Prophets and politicians often collide as they orbit the same world with different social interests and moral purposes. Prophets thunder difficult truths that shake the culture to its core. "I have not come to bring peace, but a sword," Jesus proclaimed of his duty to disturb the social order. That same duty fell to King as he angered millions of whites—and scared many blacks—in challenging the white supremacy that was the lifeblood of social inequality. Even though King lashed out at injustice in love, he was widely viewed as a pariah who undercut democracy and disturbed the racial peace. But King believed that any peace that rested on injustice was false and fleeting. Politicians, on the other hand, often aim to quell social disturbance and keep the peace at nearly all costs. Their function is to preserve as much as possible the smooth operation of society and to make the machinery of governance effective. Politicians seek to unite disparate concerns in a manner that balances group interests and the greater good. Still, political calculations of what's good for society often shred the interests of the most vulnerable and powerless—those for whom prophets speak. Obama's pledge to respect such folk in his presidential tenure drew millions to his historic campaign. But unavoidable tensions rise in the effort to appease all sides in bringing together groups with competing moral interests. We got a glimpse of this when Obama invited Pastor Rick Warren to offer the inaugural prayer, angering gays and lesbians, and their allies, who criticized Obama and objected to Warren's homophobic beliefs. Unlike politicians, prophets feel compelled to fearlessly identify with the constituencies they believe to be mistreated and aggrieved. Prophets also take up unpopular causes and cast caution to the wind—think of King speaking out against the war in Vietnam, angering President Johnson and alienating him from most civil rights leadership. Or think of King's valiant defense of the poor even as much of the nation ignored their plight. King pledged support to the Poor People's Campaign, and to the sanitation worker's strike in Memphis, even as his staff expressed profound misgivings about his direction. King was unrelenting in his assault on poverty, war and racism, believing they were intertwined in a vicious strand of suffering. Prophets must also wrestle with the ugly evident and the invisible fatal. Open, upfront bigotry is the ugly evident; subtle, underground racism is the invisible fatal. Prophets must call attention to both as they war against the scourge of oppression in face and skin, and in structure and system. King did this with extraordinary intelligence and valor. Obama has elected a different route: As a pioneering political figure who has sought to serve in the mainstream, he has bravely pledged to move beyond the poisonous prejudice of the past. As America made history by making Obama president, it proved that it was willing to offer Obama the chance to implement his goal of racial healing. Some have mistakenly assumed that such a gesture proves we are post-racial, a term Obama has never used. Post-racial impulses seek to eradicate—not persistent racism per say—but the memory and history of racism as the predicate of social progress. Post-racism requires a great deal of denial, pretension and amnesia; it sees progress in the repression, not the uprooting, of race. Post-racism also demands the avoidance of race—confusing the positive recognition and affirmation of racial identity with the paralyzing preoccupation with racial privilege and hierarchy. Thus all signs of race are viewed as symptoms of racism. Blackness, for example, becomes a problematic identity because it resonates in the realm of race as a marker of difference. The post-racial quest is to deny difference; the result is sad: It reinforces a racial status quo that already undermines black folk, especially the middle classes and the poor. Obama's success should not move us toward a post-racial society, but it should move us toward a post-racist society. A post-racist society aims for racial justice and harmony by removing racial impediments and social obstacles that prevent folk from flourishing. A post-racist society creates opportunity for all people to realize their ambitions and goals without unjust restraints and unfair barriers. King and Obama—the prophet and politician—have much in common: the racial roots they share and mending the nation's tattered racial history. But King's voice rang as a trumpet against injustice by challenging society in civil disobedience and in breaking unjust laws. As president, Obama is the most powerful man in the world, sworn to uphold the laws of the land and bring prosperity to its citizens. Barack Obama may be the realization of King’s dream, but he is not the extension of King's prophetic ministry. Neither should he be expected to carry that mantle. As the first president who is black, Obama has made millions of black hearts, including mine, swell with pride. But he is a politician, not a prophet, and should be judged as a political figure. It may be on King's shoulders that Obama has climbed to reach farther than any other black person before him, but it is King's vision and work that made his efforts possible. The prophetic and the political are both crucial elements of our success, and survival, as a people.