Those who fight are human beings; those assisting them are the angels of God; and those opposing them are the evil demons.
Failure results not from the enemy’s formidable strength, nor because the protectors are careless: rather, it is because the fighter is unprepared that the knowledge of God vanishes and fails.
Our Lord Jesus Christ, who handed on to us everything necessary for salvation, bestowed on us power “to trample serpents and scorpions, and all the powers of evil” (Lk 10:19).
And together with all his teaching he handed on to us what he himself did when tempted by Satan (Mt 4:1-11; Lk 4:1-13).
And so in the moment of battle, when the demons attack and hurl weapons against us, we too (like Christ), must speak out against them from the text of sacred Scripture.
In this way their foul tempting-thoughts will not persist in us, enslaving the soul through sin arising from action, staining it and casting it into the sin of death. As scripture says, “The soul that sins shall die” (Ez 18:4).
For when sin has not yet entered the mind it is still possible to speak out against the evil, vanquishing it easily and rapidly.
[...] For this reason we have carefully selected the right words from the Scriptures, so that armed with them we may “vigorously drive away the Philistine” (cf. 1 Sam 14:52) while standing fast in battle, like powerful men and warriors of our victorious king, Jesus Christ.
But we know this, beloved: that to the degree that we withstand them in battle and answer the demons back, they will be embittered to that degree against us.
We are instructed in this by Job who said, “No sooner do I start to speak, then they wound me.” (Job 6:4 LXXX). And David speaks similarly: “When I speak out for peace, they make war against me” (Ps 119:7).
But it is not right for us to be afraid of them: instead, we must withstand them confidently in the power of our Savior.
For if we believe in Christ and carefully keep his commands, we will cross the Jordan and take Jericho, the “city of palms.” (cf. Jdg. 3:13 LXX).
In this battle we need the spiritual weapons, (cf. 2 Cor 10:4) of steadfast faith (Col 1:23) and teaching, which imply: perfect fasting; mighty victories; humility; calm stillness; slowness to react or utter imperturbability; and prayer without ceasing. (cf. 1 Th 5:17).
Evagrius Ponticus (345-399): Antirrhetikos (Prologue), translated by Luke Dysinger OSB.