Lines 337-362: What are the “two opposing forces” King discusses in this section?

The two opposing forces are the "force of complacency" and the force of "bitterness and hatred".

One is a force of complacency, made up in part of Negroes who, as a result of long years of oppression, are so drained of self-respect and a sense of "somebodiness" that they have adjusted to segregation; and in part of a few middle class Negroes who, because of a degree of academic and economic security and because in some ways they profit by segregation, have become insensitive to the problems of the masses. The other force is one of bitterness and hatred, and it comes perilously close to advocating violence.

What does king fear and what does he want to do?