Because violence is never the solution.
Martin Luther King Jr. is known for his nonviolent protests.
In 1963, he was successful in the march on Washington, and in 1964 he won the noble peace prize. He works for civil rights for African Americans and gave the "I have a dream" speech on August 28th, 1963. King wants you to fight alongside him, but peacefully. You can accomplish more using nonviolence than you can using violence.
"Darkness cannot drive out darkness, only light can do that. Hate cannot drive out hate, only love can do that." ~Martin Luther King Jr.