When they say, "Give us reparations to atone for America's original sin of racism!"
And you say, "OK, if that means the slate's wiped clean and no more affirmative action, hate speech laws, or guilt-tripping white people in general, name your price."
Their defining morality, which is founded on absolution for racism being impossible, will compel the Cultist to silence, or to admit that racism can never be atoned for.