In order for Socialism to be workable, it is necessary for all members of the society to be the same. When you have differences in terms of race, religion, etc., then resentment begins to creep in. "I don't want so-and-so who is of a different race/religion/se*ual orientation to get the same share as myself - they don't deserve to have the same, because they aren't the same as me." This has always been the problem with socialist movements in the past. If the U.S. citizenry had been composed of a single ethnic group back in the 1930's, Socialism would have triumphed, because it is human nature to wish your own kind well. But because the U.S. was composed of a highly diverse collection of ethnic grouping, Socialism fell flat. The whites didn't want to share on an even level with the blacks, the Protestants didn't want to share on an even level with the Catholics (or Athiests), the Irish, Italians, Germans, etc. were all interested in looking after their own, and everyone else be damned. That is human nature. In order for Socialism to succeed, it must adapt to the human need to segregate. Socialism can only succeed if it is applied within each particular xenophobic group.