King did a lot more than “flirt” with Socialism. Look up Jack O’Dell, Bayard Rustin, Stanley Levison, to name just 3.
It’s the main reason why the FBI started wiretaps-although contrary to popular belief, J. Edgar Hoover didn’t initiate this on his own-he was acting on orders from his boss, Bobby Kennedy, who was acting on orders from his boss, John F. Kennedy. I think JFK drafted the Exec. Order for this in Oct 1963, a month or so before his death.
I can’t say I’m an expert on King’s life, but I do know that he was a lifelong Republican, which was only natural since all black people were Republicans before the sixties generation switched things up. Being a thouroughgoing Christian, I’d assume he was a social conservative as well. Being a revolutionary, however, couldn’t help but push him in the other direction.
If I had to venture a guess, I’d say his opposition to the Vietnam War (started by the Democrats, by the way) and his constant elbow-rubbing with radicals gradually warped his mind into buying into more of a liberation theology view of the world. But that’s just a guess.