In the first paragraph, MLK addresses the clergyman's words concerning the timing of the movement being "unwise and untimely", stating that he didn't have to take the time to answer the clergyman's questions, but because he respects them, he will answer their letter.
King's goal in issuing his "letter from a Birmingham jail" was to address criticisms directed against him by individuals who unarguably should have known better. The teachings of Jesus, he repeated, provided for the nonviolent activities that were solely intended to correct injustices.