Martin Luther King, Jr. Day is an American federal holiday that marks his birthday, observed this year on January 15.
In his speech to Congress in September of 2015, Pope Francis lifted up four Americans who worked for social justice. Dorothy Day and Thomas Merton were Catholics. Abraham Lincoln and Rev. Dr. Martin Luther King, Jr. were not Catholics.
Dr. King was the chief spokesman for nonviolent activism in the Civil Rights Movement, which successfully protested racial discrimination in federal and state law.