As cliche as it sounds, I still marvel at his I Have A Dream speech. It is a marvel of rhetoric and too many people have tried to imitate with its lofty rhetoric and his echoing voice.
I have always held his principle of a Color Blind Society as the true end goal of the Civil Rights Movement. Anything which seeks to sub-divide us by race is antithetical to the American Dream.
My father began working with American doctors at Clarke Air Base in the Philippines. I once asked him at dinner if he ever experienced racism from the white doctors there. He he gave a little shrug and said "Sure," and then continued eating. When I asked him how he handled it, he said, "I worked harder than anyone to be the best doctor there so that they knew to respect me."
To me, that is best way to fight back against racial bigots. Success is the best victory. But that only comes with hard work and perseverance. My dad had no chip on his shoulder over ill treatment. He figured you're going to get stupid people in life. The only thing to do is be excellent.
On a lighter note, there is a reason beyond his importance that MLK is revered today as a secular saint. Ask any school child about him, and they will say that he is a great man. How do children know this intuitively? Because they get the day off of school because of him.
Ask them who the greatest presidents are and they will say Washington and Lincoln? They get a day off of school because of them too.
You can imagine how important Jesus is: you get 3 weeks off because of Him. He must have been great!