"Our lives begin to end the day we become silent about things that matter."
This quote, attributed to Rev. Martin Luther King, Jr., is likely a paraphrase of original language that was slightly different. The closest statement your WorshipWeb Curator could find is this excerpt from Rev. King's sermon on courage, delivered on March 8, 1965 in Selma, Alabama:
"A man dies when he refuses to stand up for that which is right. A man dies when he refuses to stand up for justice. A man dies when he refuses to take a stand for that which is true."