Martin Luther King Jr. taught nonviolent protests and working through the system to change it. He wanted to show the establishment that it was time to change through peaceful means.
The Black Panthers, in the other hand, wanted to show the strength of the black man. They believed the only way they were going to get change was through force and threats.
I think the black militancy of the 1960s hurt the cause of civil rights. The people who held outdated beliefs about blacks that they were savage and a lower race than whites took the violence of the Black Panthers as proof of their bigotry. They didn't even hear the peaceful messages of MLK and others like him. It took a lot longer to get equal rights legislation passed than I believe it would have without the actions of the Black Panther. Hope I helped :D