I don't think he was a devil, nor was he an angel. I think that because of his first hand experience with racism, Malcolm X developed a radical opinion against all white people. Then he turned to the Nation of Islam religion. Afterwards he traveled to other countries and saw other "Muslims" that had "white" skin. This made him realize the injustices that were happening in the U.S. was not what was happening in other countries.
You can tell that he was changing and his heart was softening toward the end of his life. He was going to leave the Nation of Islam because he saw immorality that was being committed by it's leader. I think that's what got him killed.
If he had not been assassinated I think he would have changed into a different kind of a person than he was in his younger years.
People should read his autobiography. It's very interesting and you can clearly see his change toward the end.