It doesn't matter if you marched with Dr. King, or even think you would have marched with Dr. King if you'd been alive during the Civil Rights movement. Racism is a pattern of power and how it is distributed in society. It's not solved by friendship. Mary Potter Engel once observed, "The most liberating question you can ask is 'Who set things up this way?'" Don't personalize racial transformation. Here's the good news: the power relations some have constructed, other people can reconstruct.
While there is much, much more to the good Rev. Dr. Brooks Thistlethwaite's column, which I urge you to read, this point cannot be stressed enough. And it is my starting point. Race is as much about skin color as rape is about sex. Both are about power and domination. You may have made friends across many racial and ethnic lines, yet still react in a way that can only be described as racist to certain circumstances. I know I do. Jesse Jackson once confessed his shame at his gut reaction of fear when he saw a small group of African-American youth walking down the sidewalk. We are programmed, regardless of skin color or life experience, to react this way, by the society in which we live. One can overcompensate one way or another, but in the end, these are all just variations on the theme of the initial, socially-constructed reaction to a given set of circumstances.
This is why I am neither impressed by the indignant denials of racism from those on the right (usually couched in very personal terms, which are irrelevant), nor by the self-flattery of whites who flaunt their cross-racial ties. While the hatred of bigots like Limbaugh and the rest of them is certainly a problem, it is not the problem. They will not change, and we should not waste time or energy worrying about them (although Lord knows we need to keep our eyes and ears open). America is still, even with a black President, a society fundamentally structured around white privilege and the maintenance of their power. We need to see that, to see the world through the eyes of a young man who gets followed around the Mall by security simply because he's black; the young woman who is denied a seat with the in-crowd because her hair is dark and curly, not blonde. We need to be able to hear with the ears of the mother who catches the mutters behind hands as she takes her child to the emergency room. Or hear with the ears of the young scholarship student at a University who is called an affirmative action case, denying not only his superior abilities, but degrading our society's modest attempt to redress some parts of white privilege and access to power.
I think the title of Rev. Dr. Thistlethwaite's column, "How To Be White", should be followed up with, "How White's Should Learn To Be Black".