The Lord Jesus Christ warned that false prophets will be loved and praised by the secular world (Luke 6:26) and that the true prophets of God are always hated and despised by the secular world (Luke 6:22-23), and Martin Luther King Jr was certainly a false prophet.
I find Martin Luther King's "I have a dream" speech very telling in light of the warning given in Jeremiah 23:25-28 about false prophets having dreams and visions.
Jeremiah 23:25-28 KJV
25 I have heard what the prophets said, that prophesy lies in my name, saying, I have dreamed, I have dreamed.
26 How long shall this be in the heart of the prophets that prophesy lies? yea, they are prophets of the deceit of their own heart;
27 Which think to cause my people to forget my name by their dreams which they tell every man to his neighbour, as their fathers have forgotten my name for Baal.
28 The prophet that hath a dream, let him tell a dream; and he that hath my word, let him speak my word faithfully. What is the chaff to the wheat? saith the LORD.
Martin Luther King Jr is lifted up and praised as a hero by so many people (including U.S. presidents, and wicked liberal Hollywood celebrities). The truth is that MLK was a theological modernist and liberal heretic in many areas of doctrine and theology.
Keep in mind, that it doesn't matter how nice he may seem on the outside, or whether or not he did a lot of good things, it's important to remember that Satan's ministers appear as the ministers of Christ (2 Corinthians 11:13-15). Jesus Christ described false prophets as wolves who come in sheep's clothing (Matthew 7:15-20).
When testing MLK's theology, it's clear that he was a false prophet and a liberal heretic.
In the National Observer, Dec. 30, 1963, Martin Luther King said the virgin birth of Christ was "a mythological story" created by early Christians.
The virgin birth fulfilled the prophecy in Isaiah 7:14, it was no mythological story, it was a fulfillment of prophecy.
Isaiah 7:14 KJV
14 Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel.
In Ebony magazine, January 1961, King said: "I do not believe in hell as a place of a literal burning fire."
That statement from King is a direct denial of Luke 16:22-26.
Luke 16:22-26 KJV
22 And it came to pass, that the beggar died, and was carried by the angels into Abraham's bosom: the rich man also died, and was buried;
23 And in hell he lift up his eyes, being in torments, and seeth Abraham afar off, and Lazarus in his bosom.
24 And he cried and said, Father Abraham, have mercy on me, and send Lazarus, that he may dip the tip of his finger in water, and cool my tongue; for I am tormented in this flame.
25 But Abraham said, Son, remember that thou in thy lifetime receivedst thy good things, and likewise Lazarus evil things: but now he is comforted, and thou art tormented.
26 And beside all this, between us and you there is a great gulf fixed: so that they which would pass from hence to you cannot; neither can they pass to us, that would come from thence.
When the rich man died, he woke up in a place of literal burning fire, and he was "tormented in this flame." Hell is indeed a literal place of fire, but King denied this scriptural truth.
There is a whole lot more that could be said, there was also King's communist ties, his involvement in adultery, his habit of being a whoremonger, among many other issues.
It's really important to NEVER esteem someone so highly like some ignorant Bible-believers esteem Martin Luther King Jr as some sort of hero of the faith (when he was nothing of the kind).
Luke 16:15 KJV
15 And he said unto them, Ye are they which justify yourselves before men; but God knoweth your hearts: for that which is highly esteemed among men is abomination in the sight of God.