Destruction of the enemy should be seen as a last resort. Enemies need to be understood. Enemies need to be educated and changed. So where should all the energy be focused? It should be focused on Love, understanding, and helping to develop. But if all the measures are exhausted, as Christ said " if they refuse to listen… treat them as you would a pagan..."
Killing the enemy is the last resort, it is on an physical level, when there is no other choice. Let's take the most difficult case — how to understand Hitler, fascism? So let's take the essence of fascism.
So fascism is an attempt to save humanity. But this is at the ‘last resort’ level. For the last 200-300 years the Church effectively eliminated the faith by introducing indulgences [forgiveness of sins for money]. If the priest forgives our sins, then we will no longer be punished for our sins by God and God is no longer needed. So people are feeling a degradation of the whole society. However, this degradation can be corrected by returning to love, and through understanding the mission of Christ.
That is degradation of society can be corrected through our development and not destruction.
However, it is much easier to simply destroy the underdeveloped than to help them develop.
The situation is comparable to ancient Sparta, where all weak children were drowned. Here the scale and boundaries of weakness were expanded where the inferior people now had mental flaws, followed by genetic and nationality flaws and so on. This is an attempt to save humanity by eliminating the inferior people.
If we consider fascism to be just evil, it will be invincible.
But if we understand that it is purely a clumsy, primitive attempt to save humanity, then we will understand how to deal with it.
It is necessary to find a better way and then the roots of fascism will be undermined.