Martin Luther King Jr. had a non-violence self-sacrificing position to prove that the group is more important than the individual. A study in some of the writings as well as the analysis of his life would help you develop strong arguments to prove the relationship between the man and the statement.
I would use 3 points of reference in developing such an argument:
1. His positions: Martin Luther King Jr. believed in social justice, resistance, reconciliation, and non-violence. Each of these values prove that he put society before himself because the consequences on the individual for rejection of these ideas was extreme. He eventually paid for his values with his life.
2. His writings: In each of his speeches and sermons, King rallied individuals to seek common purpose in pursing justice for all peoples. His "I have a Dream" speech particularly employs the theme of unity.
3. His lifestyle: Many people today preach one thing and then do another. King participated in sit-ins, he went to jail for his positions, and he marched. Each of these actions demonstrate that he did not just say how he felt, he acted on it.
All of these took place within the Civil Rights Movement over issues of racial equality. Therefore, tension was high and conflict flared regularly.