I would argue that Dr. King was far more radical than even you acknowledge. He spoke to more than just a sense of injustice, more than just a desire to right individual wrongs, but a deeply religious view of the universe which is completely at odds with capitalism.

One of his early influences was Edward Bellamy. Bellamy is most known for his best-selling novel of a utopian (and unapologetically socialist) future, Looking Backward. His novel influenced a whole generation of activists in the late-Nineteenth and early-Twentieth century. Less well-known was a tract Bellamy wrote in his youth — The Religion of Solidarity. King discusses this tract in his early letters. Bellamy there expressed the (old) idea that we are not just individuals, but part of something larger, what he called the “Universal.” The realization of the Universal is what brings us together, and prevents us from hurting each other, which would only be hurting ourselves.

King expressed this view of the world throughout his writings and speeches. For example, he concluded his 1958 essay, An Experiment in Love (published in his book, Stride Toward Freedom: The Montgomery Circle), with this:

Whether we call it an unconscious process, an impersonal Brahman, or a Personal Being of matchless power and infinite love, there is a creative force in the universe that works to bring the disconnected aspects of reality into a harmonious whole.

Capitalism, in contrast, is based on the belief that we are separate entities, interacting only through discrete “market” transactions. This unity, this “harmonious whole” as Dr. King put it, is the true opposite of both racism and capitalism.