**several Protestant countries became communist...East Germany and Czechoslovakia come to mind.**
IIRC Germany and Czechoslovakia “became” Communist when they were taken over a larger nation, one that was Orthodox before it became atheistic and Communist. Remember the USSR?
Russia became communist because of incompetent leadership on the part of the Czar and the Duma (something that still goes on today), the unbelievable poverty and the true exploitation of the masses. That the communists exploited them as well as practicing genocide is another matter.