While we all know 'I Have a Dream,' it is MLK's 1963 letter in response to clergy from jail in Birmingham that speaks most powerfully and timelessly about the meaning of religion. He wrote about churches, but I know the same words apply to synagogues as well.
"On sweltering summer days and crisp autumn mornings I have looked at the South's beautiful churches with their lofty spires pointing heavenward. I have beheld the impressive outlines of her massive religious education buildings. Over and over I have found myself asking: 'What kind of people worship here? Who is their God?....'
"There was a time when the church was very powerful--in the time when the early Christians rejoiced at being deemed worthy to suffer for what they believed. In those days the church was not merely a thermometer that recorded the ideas and principles of popular opinion; it was a thermostat that transformed the mores of society...
"But the judgment of God is upon the church as never before. If today's church does not recapture the sacrificial spirit of the early church, it will lose its authenticity, forfeit the loyalty of millions, and be dismissed as an irrelevant social club with no meaning for the twentieth century."
Any of us who call ourselves religious should reread the whole letter, year after year. It is still addressed to us.