Has any major U.S. politician in modern times ever given a speech about race in America as unflinching, human and ultimately hopeful as the one Barack Obama delivered yesterday? Whether or not the speech satisfies critics of Mr. Obama's close relationship with the Rev. Jeremiah Wright, this remarkable address was one for the history books.

And it was a speech only Barack Obama, with his complicated racial background and cool charisma, could have given. His challenge was enormous: to explain why he has spent two decades worshipping in a black church whose pastor – a man Mr. Obama calls his spiritual father – at times denounces the very country that Mr. Obama seeks to lead.

Many political observers had written the Obama campaign off. After yesterday's magnificent address, we beg to differ. The Obama speech was effective for several key reasons:

He decried Mr. Wright's offensive remarks but said they do not represent the totality of the man or his church. In any case, said Mr. Obama, these folks are like family to him, and you don't disown your family. He portrayed his mentor as a figure of tragic pity: a man whose generation suffered real humiliation in segregated America, the memory of which "distorts reality."

He emphasized that his former pastor erred in assuming that America had not changed and could not change – even though the presidential candidacy of a member of his own congregation refutes that belief. "But what we know – what we have seen – is that America can change," Mr. Obama said. "That is the true genius of this nation."

Mr. Obama explained that black anger has a historic context and cannot be denied. He also explained that white resentment has a context and cannot be denied, either. Both sides have legitimate claims, he said, but they err in magnifying grievances. We can continue to nurse our anger privately this election year and remain in this "racial stalemate" – or we can refuse it and come together to solve our problems.

Throughout the speech, Mr. Obama portrayed America's racial history as fraught with tragedy and moral complexity but insisted that nothing can erase the fact that all Americans are, in some sense, family. That our destinies and our freedoms are, as the Rev. Martin Luther King Jr. taught, inextricably bound.

The true genius of the Obama speech was both in its frankness about the nation's racial problems and in its insistence that America is not defined by the evil of its past, but rather by its ability to repent and to be redeemed by our efforts to renew the bright promises of our nation's founding.

It was possibly the most important major speech on race in America since Dr. King died, and it probably saved Mr. Obama's candidacy. If, in the end, Barack Obama does not win the nomination, let it never be said that he did not serve his country.