Your quote does not resemble the Civil Rights movement at all. And I was there in the 60's.
It was the Constitution of the United States that motivated everybody I knew, not "communism".
Nobody cared about "communism" or the state ownership of the means of production, all that crap!
The American Constitution was our highest calling and our guiding light.
I was in Mississippi in the 60's and everybody I knew in the civil rights movement was motivated by principles found in The Constitution.
It was American law that was the primary motivation.
And MLK spoke frequently about the US Constitution as the guiding light, also the Emancipation Proclamation, and the Declaration of Independence, "life liberty and the pursuit of happiness", "all men are created equal", etc, read his speeches, it is all about the US Constitution and US principles:
I, and others, were in Mississippi to help people register to VOTE, to exercise their constitutional rights, and some of our fellow "white people " were trying to kill us, in fact they did kill some of us. We were no there to advocate "communism " or to divide people.
You accuse the civil rights movement of "intensifying racial strife"? Apparently you do not know how much strife there already was!
At that time black people could and did get beaten or killed for simply trying to vote.
The local "authorities" were brutal, local cops could rape young black girls and beat and intimidate anybody without any fear of legal consequence.
I'd call that "racial strife"!