A coalition of African American faith leaders is invoking the words of Martin Luther King Jr. as it tries to revive the debate over the nation's gun laws and calls on Congress to toughen background checks for firearms purchases.

In an open letter timed to coincide with the 50th anniversary celebration of the March on Washington, leaders of predominantly black congregations across the country wrote that they have an obligation to future generations to "sound the clarion call to end gun violence in our communities."

"On this national anniversary, we must not only herald the progress we have made as a country, but we must take stock of the detrimental decisions and policies of indifference that turn a blind eye to the alarming magnitude of lives cut short too soon," the clergy members wrote in the letter.