What we now call “liberalism” differs from malevolent ideologies of the past in that moral depravity is not merely a characteristic or even defining feature but the central objective. The most destructive ideologies in human history have been communism and Islam. But these ideologies are merely evil. Moonbattery is meta-evil, embracing and incorporating all else that is evil.

For example:

Mao killed 65 million of his own people. That lends him cachet among progressives. His body count will be exceeded if they prevail.

For another example:

Only by pursuing wrongness as an end in itself is it possible to reconcile LGBTism with Islam:

On tips from Kevin R and Wiggins.