Right off the bat, Dr. King lets us know he's in jail at the moment. He says that, while he doesn't usually answer criticism, he's making an exception in this case because his interlocutors are "men of genuine good will" (1).

These words could be taken in a couple of different ways:

(1) As flattering to the eight white clergymen—that Dr. King would take their criticisms seriously enough to want to answer them directly.

(2) As a subtle dig at them for having made an argument bunk enough to necessitate a complete and thorough debunking and deconstruction, MLK style.

We kinda like the second one.