Beware of the counsels of the evil one, if he should come in the guise of one professing truth to beguile you and lead you into deceit. Even if he should come to you as an angel of light, do not believe him or obey him: for he is apt to fascinate the faithful by the attractive semblance of truth.
When the enemy tempts you with thoughts of faithlessness, with all your heart say, I believe completely whatever the Church believes, whatever Christ says in the Holy Gospels, whatever the Holy Apostles and the Holy Fathers said. 'I don't, however, believe you, devil, for you are a liar and a thief.'
The evil one cannot comprehend the joy we receive from the spiritual life; for this reason he is jealous of us, he envies us and sets traps for us, and we become grieved and fall. We must struggle, because without struggles we do not obtain virtues.
Just as our Lord is solicitous about our salvation, so too the murderer of men, the devil, strives to lead a man into despair... Judas the betrayer was fainthearted and unskilled in battle, and so the enemy, seeing his despair, attacked him and forced him to hang himself; but Peter, a firm rock, when he fell into great sin, like one skilled in battle did not despair nor lose heart, but shed bitter tears from a burning heart, and the enemy, seeing these tears, his eyes scorched as by fire, fled far from him wailing in pain.
When you intend to do something and see that your thought is perturbed, and if after invoking God's Name it remains perturbed even by a hair's breadth, know from this that the action you mean to commit is from the evil one and refrain from commiting it. For nothing done with perturbation is pleasing to God.
Let us be sure, then, that God will not give spiritual gifts - the gifts of understanding, of faith, of love, of purity, of prophecy, of working wonders, of power over demons, of insight, of sight of the heavenly world, to him who has gambled with and made evil use, like the Prodigal Son, of the gifts of bodily health, honor, wealth, success among men or knowledge of this material world, or some other skill or capacity.
Since self-love is the origin and mother of evil, when this is eradicated all the things which derive from it are eradicated as well. For when self-love is absent, not the slightest trace or form of evil can exist in any way at all.
A mind from which the thought of God has been carried away and which has thus become far removed from remembering Him, is also indifferent to sin with the outer senses. For such a mind can guide neither the hearing nor the tongue, since zest to work on itself has gone out of it.
There is nothing more efficacious against the wiles of the devil, dearly beloved, than the kindness of forgiveness, and the bountifulness in charity, by means of which sin is either avoided or overcome.
Wherever we are and whatever our circumstances, the enemy always tries to prevent us from actively responding to the call. Pray for help. For help that you may never fail to respond. And beware lest, having received help and having done the right deed because of it, you should grow proud and acquire the habit of condemning others, in the secret chambers of your heart. Beware! For this would make all the fruits of your good works wither.