... To be more specific: it is universally acknowledged that Marx was a virulent anti - semite ...
Universally acknowledged, is it? A bold claim, don't you think?
Psychologists refer to this as "social proof." Everyone believes it, so it must be so. Not terribly rational. You can read all about it in Aaronson's Social Animal or Cialdini's Influence, Science and Practice. Logicians simply call it appealing to the mob (argumentum ad baculum).
Please remind me. Which one of us is supposed to be ideologically purblind?
Some years ago a compendium of all Marx's writings on jews was published under the title "A World Without Jews." No one familiar with his writings, or who had read historians like Paul Johnson's biographical material would be in doubt of his anti - semitism. You are simply being obtuse.