In his Letter from a Birmingham Jail (1963), King applied Amos to his situation, quoting from Amos 5:24. Amos gave his message to the Israelites in 750 BCE. Amos warns the people of Israel that the Lord is displeased with their behavior. People are overly concerned with earthly possessions, bodily desires and there is a shallow adherence to their religious values. Amos tells the people that God will soon judge them for their sins.
"But though I was initially disappointed at being categorized as an extremist, as I continued to think about the matter I gradually gained a measure of satisfaction from the label. Was not Jesus an extremist for love: "Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you." Was not Amos an extremist for justice: "Let justice roll down like waters and righteousness like an ever-flowing stream." Was not Paul an extremist for the Christian gospel: "I bear in my body the marks of the Lord Jesus." Was not Martin Luther an extremist: "Here I stand; I cannot do otherwise, so help me God."
He also quoted Amos in the "I Have a Dream" speech, 5 months after the above letter – Dr. King declared, “we will not be satisfied until ‘justice rolls down like waters, and righteousness like a mighty stream.’”
Here is a musical adaptation of the words from Amos
Amos inspired Dr. King’s entire ministry.
In 1952 or 1953, while studying for his doctorate in divinity, Martin Luther King wrote these notes:
"5:21:24 — This passage might be called the key passage of the entire book. It reveals the deep ethical nature of God. God is a God that demands justice rather than sacrifice; righteousness rather than ritual. The most elaborate worship is but an insult to God when offered by those who have no mind to conform to his ethical demands. Certainly this is one of the most noble idea[s] ever uttered by the human mind.
"One may raise the question as to whether Amos was against all ritual and sacrifice, i.e. worship. I think not. It seems to me that Amos’ concern is the ever-present tendency to make ritual and sacrifice a substitute for ethical living. Unless a man’s heart is right, Amos seems to be saying, the external forms of worship mean nothing. God is a God that demands justice and sacrifice can never be a substitute for it. Who can disagree with such a notion?
Amos’ emphasis throughout seems to be that justice between man and man is one of the divine foundations of society. Such an ethical ideal is at the root of all true religion. This high ethical notion conceived by Amos must alway[s] remain a challenge to the Christian church. "
On May 2, 1954, as a 25-year-old minister giving his first sermon as pastor at Dexter Avenue Baptist Church in Montgomery, he preached, “I have felt with Amos that when God speaks who can but prophesy.” (Amos 3:8.)
On December 5, 1955 — the first day of the Montgomery bus boycott — Dr. King was just 26 years old when he was elected President of the Montgomery Improvement Association, which had called the boycott. He was beginning the second year of his ministry and needed 15 hours to prepare his Sunday sermons, but that evening had only 20 minutes to prepare the most decisive speech of his life to the thousands who packed the mass meeting at Holt Street Baptist Church:
"We are here this evening for serious business. We are here in a general sense because first and foremost we are American citizens, and we are determined to apply our citizenship to the fullness of its means. We are here because of our love for democracy, because of our deep-seated belief that democracy transformed from thin paper to thick action is the greatest form of government on earth. But we are here in a specific sense, because of the bus situation in Montgomery. We are here because we are determined to get the situation corrected.. . .
My friends, I want it to be known that we’re going to work with grim and firm determination to gain justice on the buses in this city. And we are not wrong, we are not wrong in what we are doing. If we are wrong, then the Supreme Court of this Nation is wrong. If we are wrong, the Constitution of the United States is wrong. If we are wrong, God Almighty is wrong. If we are wrong, Jesus of Nazareth was merely a Utopian dreamer and never came down to earth. If we are wrong, justice is a lie. And we are determined here in Montgomery to work and fight until justice runs down like water and righteousness like a mighty stream."
On January 30, 1956, during the bus boycott, white supremacists firebombed Dr. King’s house while Dr. King was away speaking. His wife Coretta Scott King and their baby daughter Yolanda were at home but escaped without injury. When he returned, he spoke to an angry crowd that had gathered at his house. He told them to go home, saying “We must learn to meet hate with love.” Five days later, he received a telegram from Julian Grayson, an undergraduate classmate at Crozer Theological Society who had become a Methodist minister. It read simply, “FIGHT ON AMOS GOD IS WITH YOU.”
His first book, Stride Toward Freedom, published in 1958, shed light on his calling:
"Any discussion of the Christian minister today must ultimately emphasize the need for prophecy. Not every minister can be a prophet, but some must be prepared for the ordeals of this high calling and be willing to suffer courageously for righteousness. May the problem of race in America soon make hearts burn so that prophets will rise up, saying, “Thus saith the Lord,” and cry out as Amos did, “. . . let justice roll down as waters, and righteousness like an ever-flowing stream.”