Answer:
The first and most important thing to remember is that "Letter from Birmingham Jail" was an exortation, and response in the form of a letter that Martin Luther King Jr. wrote in 1963 to the public statements made by eight white religious leaders on the matter of Dr. King´s support and even encouragement, as well as participation, of the nonviolent protests and sit-outs on the part of African Americans and white anti-segregationists. Because these eight leaders use both political and religious arguments to invite Dr. King to retract from his support and his involvement in the movements against racial segregation, Dr. King responds to each of their arguments with an appropriate mixture of political reasons that are supported and anchored in religious belief, and most importantly, in the fundamental principles of the rights afforded to humans by God. Also, because these leaders are all religious, and therefore well-versed in religious matters, Dr. King uses that, in which he is also trained, to respond argument with argument.
Essentially, Martin Luther King Jr. does a masterful combination of his religious background, and his knowledge of the Scriptures and the tenets of the faith, and which are not unknown to these eight men, and his political knowledge and uses them both as twin means of support for his arguments in favor of the anti-segregation movements. He uses political reasoning, laws, obedience and civil disobedience that is acceptable by the laws of men, (the U.S Constitution in this instance and the mandates of the Supreme Court), and grounds them on the religious tenets of the Christian faith to show whether a law can be acceptable, or not, if it is morally right or not, and therefore should, or should not be obeyed. In summary, Dr. King disarms the arguments of the eight Christian leaders by utilizing the two points of discussion that are being used: the importance of laws, upholding them to achieve political stability and the greater good, and the justification, or lack of it, by the Christian faith, of these laws.