MLK is the primary example of nonviolent resistance as the only way to bring about changes in civil rights. However, there are allusions to others; Christ for example.
The song is about singular "people" (including Christ as man) that lived their life with pride. Not in a boastful way, but with the pride a person has when their thoughts and actions are motivated by they understand and full awareness of the dignity and sanctity of ALL human life.
The song is a tribute, illustration, or reminder to us, of martyrs to this ideal. It speaks to how they lived their life with an inner Pride in all of humanity and that this Pride is really an expression of God's love for all of humanity. These people did what they did because they were trying to spread this message of God's love for all of mankind.
This began as a song about US president Ronald Reagan. Bono had lyrics written condemning Reagan for an arrogant pride that led to nuclear escalation, but it just was not working. "I remembered a wise old man who said to me, don't try and fight darkness with light, just make the light shine brighter," Bono told NME. "I was giving Reagan too much importance, then I thought Martin Luther King, there's a man. We build the positive rather than fighting with the finger."
King was killed on a Memphis motel balcony on April 4, 1968. Bono sings "early morning, April 4," but King was actually killed in the evening. Bono has acknowledged the mistake and sometimes sings it as "early evening, April 4."
Chrissie Hynde (lead singer of The Pretenders) sang backup. She was married to Jim Kerr of Simple Minds at the time and was thanked on the album as "Mrs. Christine Kerr."
