They'd prefer to believe their little myth that "real Christians have always supported the Jews." Obviously, it ain't so.
However, I do not agree that "Christians" are to blame for the Holocaust, nor have I ever subscribed to the notion that any one group has to "apologize" to any other group for things done in past generations. That's a modern-day socialist contrivance meant as a tool to cause division and strife so that their policies can sweep in to "save the day" (c.f. the "African slave reparations" movement of which David Horowitz has written extensively).
And it is not Christ Himself who has perpetrated these things on the Jews. In fact, Christ commanded us to love our neighbors, and He took pains to define "neighbor" as any other person on the earth, not simply those who look, talk and worship like we do.