In the mid-1970's, radical black theologian William R. Jones (author of Is God a White Racist?) gave a speech at my alma mater, Wesley Theological Seminary. In that speech, he made the suggestion that the near-canonization of Martin Luther King, Jr. was symptomatic of the history of white America finding an acceptable black man as "leader", whereas the African-American community was not compelled to follow suit; if it had multiple sources of community strength, adhering to a wide range of views (Jones cited Malcolm X in particular), so much the better. Considering the academic Dean at the time, J. Philip Wogaman, had marched in Selma and suffered with the folks there with King, this was, quite literally, a fart in church.
Yet, Jones' point needs to be heard as a legitimate criticism of the near-universal acclaim King was already receiving at that time.
This is not to suggest that, in the period when King and the SCLC was most active, it was not perceived as dangerously radical. Indeed it was; J. Edgar Hoover did everything he could to undermine King. King's message, especially after 1965, when he pointed out the continuity between the struggle for Civil Rights and the struggle against the war in Vietnam, was far more radical than the kind of "Kum Bah Ya" message we too often get today.
During a seminar on Liberation Theology, I pointed out that, for all that King is so beloved for his "I Have A Dream" speech, the reaction of the southern power structure showed that, despite the best efforts of King and others, "non-violence" was not possible as a tactic for social change, precisely because the power structure would use violence to suppress any attempt at social change. I still believe that, despite the earnest quest for social justice through non-violence, this is true.
Other responses at the time, including black separatism given voice (for a time) by Malcolm X and the Black Panthers, criticized not only King's nonviolence, but his goal of social and political integration. They also were far more militant in their approach to the white power structure, and there is more than enough reason to grant their position a fair hearing than to react to it because it refuses to denounce violence as a tactic for social confrontation (not necessarily change). The Panthers, in particular, were a very visual threat precisely because they were armed, wore fatigues, and used a violent rhetoric of opposition that guaranteed them not only press coverage, but official hostility as well.
Except, for the most part, the Panthers violence was rhetorical. Dedicated to creating community support networks, feeding the hungry, education support, and other local concerns, the Panthers were merely exercising their quite legal right to bear arms in their own defense and the defense of their community. Far more than right-wing militia types who believe that the ZOG is preparing to have UN troopse swoop in and steal our guns and make us all swear fealty to Allah and the mullahs in Iran (as opposed to the former belief it was all about the communists), the African-American community's position on the threat of force to meet official terrorism has more than a little moral legitimacy.
While the history of the Panthers is ambiguous at best, I believe their original program, violent rhetoric included, has more than enough claim to being a morally and even politically legitimate position. While I understand why many are turned off at any call to violence under any circumstances, I am not, and while I would not necessarily accept an unprovoked violent attack by any individual or group, the Panthers' position, one of defense against a racist power structure, is one I find, at the very least, a nice "up yours" to the establishment.