Inquiry #2: Dr. King

In a "Letter from Birmingham Jail," Martin Luther King classifies the Negro community into two groups. These "forces" fall into categories that come up in a later topic of extremes and they are the force of complacency versus the force of bitterness and hatred.
This made me wonder how Dr. King would join these two groups, fighting for the same cause, to come to some kind of agreement as to how they should resolve things. Did this cause discrepancies amongst the oppressed? He states that some of the middle class Negroes were just comfortable with the way things were so they did not feel the need to do anything about the unjust situation. This had to have outraged people that were not in the middle class, who suffered miserably but watched their "brothers" do nothing about it. While on the other hand, some people were filled with bitterness and hatred and wanted to take things in their own hands and most likely make things worse for themselves. How did Dr. King address these two very different groups of people and bring them together. And on the topic of extremes, what else would you expect in such a desperate situation. Does everyone have the inherent desire to turn to extremes if they feel like they have no other choice? And who is to blame that it even got to the point for people to consider such extremities?
Maybe the middle-class Negroes did care but they were too scared to say anything for fear or persecution. What would you do if you could possibly be beaten or arrested and seperated from your family if you stood up for complete strangers because it was right? I doubt that people who did act out of hatred were evil people. Perhaps they felt forced to act this way because there was no other way to bring attention to the evil that provoked what they felt they had to do. To what extremes will people to go to accomplish what they think is right?