As for the Dark Enlightenment, let’s just call it fascism and leave it at that. It is against the free thought of the real enlightenment, which tells all kinds of authorities, both police and ecclesiastic, to shove it.

The alt right’s real purpose is to justify capitalism, the domination of the bosses. Catholic social doctrine can help, but it only goes so far. Something akin to cooperative socialism, which includes democratizing both ownership and control of the enterprise is needee to stop the vulnerability of the white working class to the alt-right, although to do so it must respect the views of the religious without becoming subservient to the Church.  Distributism is a quaint idea, but will not work in practice.

As for countering the alt-right leadership, ridicule may be best, although sometimes that just radicalizes their followers, so it must be really funny.