Yes, the Communist Jews were secularized, no question. But they were also Internationalists, rootless and in many cases hateful of the tradition, of the religion, of the patriots, whom they murdered, as in Poland, where after the war (according to your link) 37% of the security apparatus were people of Jewish descent (where in the society as a whole the surviving Jews were then perhaps 1%.) After the war? Wait, where did they come from, weren’t they all murdered by those mythical Nazis? They came to Poland from Russia, and some didn’t even speak Polish.
And yet it was Gomulka and his fellow Polish Commie stooges that had most of the remaining Polish Jews kicked out of the country in 1968.