The correct answer is to illustrate the depth of his religious faith.
Explanation:
Martin Luther King Jr. was an American activist and also a spokesperson of Civil Rights Movement. It is known that the biggest influences on him were nonviolence and faith through Christianity. The mentioned Letter from Birmingham Jail is also known as The Negro is your brother, and it is an open letter that emphasizes nonviolent methods to face racism. In the quote, both influences are easily seen, like the already mentioned nonviolence, King also adds emphasis to his Christian faith with the sentence.