That is not necessarily a bad thing.
He was a human being first and foremost - and flawed. As was King David and many figures in the Bible and otherwise, who were great men of God.
(I dont doubt that MLK may have been unfaithful in his marriage nor that Marxists were part of the Civil Rights movement...but some of the FBI stuff on him is no different than the hoax-like “files” Mueller and his team have on Trump and Russia “collusion.”)
Secondly, MLK was the REVEREND Martin Luther King Jr. A Christian. A Baptist. And a preacher.
Thirdly, he had plenty of reasons to decry the social ills and abuses defining post-Civil War American society a century onward. Racism is a very real sin.
Fourth, he was a pacifist - weary of any violence including the Vietnam War.
But Fifth, he was a Patriot and he was not ashamed to lay the words and principles of our founders as the bedrock to his value system - including the words penned by former slaveowners.
“I have a dream that one day this nation will rise up and live out the true meaning of its creed: We hold these truths to be self-evident, that all men are created equal...”
” I have a dream that one day on the red hills of Georgia, the sons of former slaves and the sons of former slave owners will be able to sit together at the table of brotherhood...”