To mark what would be the 90th birthday of civil rights icon Martin Luther King Jr. this year, Rev. Dr. William Barber II—architect of the Moral Monday movement in North Carolina and co-chair of the national Poor People’s Campaign—delivered a sermon on Monday about what is means to preach and why, as Dr. King exemplified, good people of all backgrounds and beliefs “must march, organize and fight” against injustice wherever it is found.

“When words are changed into deeds of liberation—that’s preaching. And anything else is just talking.” —Rev. Dr. William Barber II”To honor Dr. King, who was always a preacher,” Barber stated, “I wrote this sermon for #MLKDay on what it really means to preach.”

Commending the powerful preaching of those who stood for social justice and the common good throughout history, Barber’s sermon highlights the fact that King stood against “racism, poverty, and war” not because it was popular, but because it was morally unavoidable. “That’s why [King] spoke as one who had authority,” Barber says.

“And not only did he do it within the comforts of a quarantined sanctuary,” he continues, “but he did it in the streets of the nation and even from the jails.”

So what is it to preach in these times of struggle?

As the central part of the sermon, and to answer that question, Barber declares:

Watch the full sermon: