Martin Luther King, Jr. was a great man. He contributed invaluably to arguably the greatest social change that has ever been worked by people here in the US. He died for his ideals. He should be honored.

Martin Luther King, Jr. Papers Project
Seattle Times Feature

At the same time, he had real character flaws. His academic writings were plagiarized. He was a womanizing adulterer.

Finally, he broke with the historic Christian faith.

He denied some of the most fundamental components of historic Christianity. He repudiated the doctrine of the deity of Jesus, and he rejected the concept that the Lord was raised bodily from the dead. King disdained the New Testament affirmation of Christ’s virgin birth, asserting that the early Christians devised a mythological story to account for the moral uniqueness of Jesus of Nazareth.

In summary, MLK was a great man who helped affect massive social change. But he was a man of deep flaws (as we all surely are). And, though many of his actions rank highly in the best of Christian tradition, Dr King was not a Christian in the historic sense of the word. Historically speaking, you have to believe in the deity of Christ to be called a Christian.