The issue, there, is that it requires them to see you as human. You cannot reason with someone who doesn't see you as human. I fear that a lot of them are beyond talking down from this cliff they've hyped themselves up to. Your well rationalized pleas will fall on deaf ears as they gleefully trample over you. Your desperate cries for mercy ignored, because while you may have mercy for them, they have none for you.
I hate to say this, but we cannot afford to give these... well... demons, neither a shred of mercy nor respite, for when they gather their strength and strike again, they will have none for us. You cannot reason with demons who want nothing more than to see you dead and broke, your kids raped and brainwashed, and they think it's funny. You have to deal with them decisively, or you will lose time and time again, because they have nameless hordes to throw at you, and you only have so much ground to lose.
We must not falter in the face of pure, unadulterated evil.