MLK jr's father was in Germany, where he read and studied some of the works of Martin Luther (the monk). It is obvious that he never studied all of Luther's writings because there was a dark period in Martin Luther's life where he wrote hatred and condescension. It is no surprise that MLK Sr didn't read those because they were heavily suppressed by germany.
The reason these writings were so suppressed was because they were used by Hitler to justify his destruction of the Jews. And Hitler did not take them out of context.
The point is that one man wrote many things, some that inspired people to create one of the largest, most powerful and wealthiest religious philosophies the world has ever known, the philosophy of the protestants.
Some of his writings, along with the writings of the Buddha and the writings of ghandi, inspired Martin Luther King Jr.
But all of these things have something in common. They all happened because of the necessity of people to reduce complex problems down to fit inside their own narrow perspective.