To me—and this is simply my thoughts on the subject as of today—Martin Luther King Jr. Day is about so much more than just the relationship between white people and black people. It's even about more than just "racism."
It's about the seemingly instinctive impulse for one human being, or group of human beings, to consider themselves superior to another person or people, for whatever reason. And all kinds of reasons exist, even today: men believing they are superior to women; one nation believing they are superior to another nation; the young believing they are superior to their elders; the rich and entitled believing they are superior to the poor and uneducated; one religion believing they are superior to all other religions; this politcal party believing they are superior to the other.
I've seen people act with cruelty or indifference (and I believe ignoring someone is just as bad as mistreating them) for the most absurd of reasons: because they were born with a disability, because they have red hair, because they talk funny.
Worst of all, we often hold dear such dark and corrosive beliefs because we have convinced ourselves that they are in fact "correct" and justified, swearing up and down that they don't stem from our own fears and insecurities but are supported by proof or reason or a Higher Power.
"The principles of the other politcal party are to blame for all our woes. God sanctions my religion, but considers yours sinful. Other people are poor because of their own bad decisions."
No. Martin Luther King Jr. Day is about accepting responsibility for all of it. Me, individually.
As O Sensei once said, "As soon as you concern yourself with the 'good' and 'bad' of your fellows, you create an opening in your heart for maliciousness to enter. Testing, competing with, and criticizing others weaken and defeat you."
The relationship between whites and blacks was simply the most relevant, and deeply personal, example of the day through which Dr. King could preach his message. For Jesus, it was the relationship between Jews and Samaritans. The message is the same. We simply MUST learn to look beyond the things that make us different. We must fight not just racism, but fight to anihilate that natural tendancy within to lift ourselves above another for any reason.
“The good neighbor looks beyond the external accidents and discerns those inner qualities that make all men human and, therefore, brothers." —Martin Luther King Jr. Strength to Love
We don't commemorate Dr. King today because his famous dream has been realized. Far from it; there is still much work to be done.
So for me, what Martin Luther King Jr. Day means is a day to stop and realize that when I assume that I'm not racist, when I'm positive that I haven't held anyone in a lesser regard—I'm mostly likely fooling myself. You and I can't just "turn off" millions of years of ingrained human behavior.
It is to me then a grave mistake to assume that Martin Luther King Jr. Day is a celebration for "someone else" simply because I'm white. That thought, in and of itself, separates humanity. I suspect that Dr. King's dream will have been realized when we as a planet have no need to even have a Martin Luther King Jr. Day.
Until then, we must practice. Every day.