What is MLK's Point?

I believe the overall point expressed in Martin Luther King's Letter from Birmingham Jail is to explain to the clergy men to whom he writes that no matter how they act against the black community, or even how the clergy men talk about making the community better for the blacks in Birmingham, it is a nationwide struggle that must be dealt with fairly. Birmingham had a history of being the richest city with the best police enforcement to deal with the acts against racism. The clergy men agreed that the acts were being dealt with in a calm and collective manner; perhaps they saw end to protests as brotherhood between races. King states a powerful truth when he says, "Just as Socrates felt that it was necessary to create tension in the mind so that individuals could rise from the bondage of myths and half-truths to the unfettered realm of creative analysis and objective appraisal, we must see the need of having nonviolent gadflies to create the kind of tension in society that will help men rise from the dark depths of prejudice and racism to the majestic heights of understanding and brotherhood." This is important because the police enforcement in Birmingham was also known for being the most violent against its victims of racism. The point in King's letter is to address what the clergymen had to say, and help them understand how the blacks only option was to take action using non-violent campaigning; collection of facts, negotiation, self-purification, and direct action.