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.
Even a pious person is not immune to spiritual sickness if he does not have a wise guide -- either a living person or a spiritual writer. This sickness is called prelest, or spiritual delusion, imagining oneself to be near to God and to the realm of the divine and supernatural. Even zealous ascetics in monasteries are sometimes subject to this delusion, but of course, laymen who are zealous in external struggles (podvigi) undergo it much more frequently. Surpassing their acquaintances in struggles of prayer and fasting, they imagine that they are seers of divine visions, or at least of dreams inspired by grace. In every event of their lives, they see special intentional directions from God or their guardian angel. And then they start imagining that they are God's elect, and often try to foretell the future. The Holy Fathers armed themselves against nothing so fiercely as against this sickness -- prelest.
For as merchants on a voyage, though they find a wind to suit them and the sea calm, but have not yet reached the haven, are always subject to fear, lest suddenly a contrary wind should stir and the sea rise into billows, and the ship be in peril, so Christians, even if they have in themselves a favorable wind of the Holy Spirit blowing, are nevertheless yet subject to fear, lest the wind of the adverse power should rise and blow on them, and stir disturbance and billows for their souls. There is need therefore of great diligence, that we may arrive at the haven of rest, at the perfect world, at the eternal life and pleasure, at the city of the saints, at the heavenly Jerusalem, at the church of the firstborn (Heb. xii. 23.). Unless a man gets through these measures, he is under much fear, lest in the meantime the evil power should effect some fall.
But let thine apparel be plain, not for adornment, but for necessary conversing: not to minister to thy vanity, but to keep thee warm in winter, and to hide the unseemliness of the body: lest under the pretence of hiding the unseemliness, thou fall under another kind of unseemliness by thy extravagant dress.
He shall be known by his crimes of inhumanity and lawlessness, so as to outdo all unrighteous and ungodly men who have gone before him; displaying against all men, but especially against us Christians, a spirit murderous and most cruel, merciless and crafty.
'And forgive us our debts as we also forgive our debtors.' For we have many sins. For we offend both in word and in thought, and very many things we do worthy of condemnation; and 'if we say that we have no sin' (I Jn. 1:8), we lie, as John says...The offenses committed against us are slight and trivial, and easily settled; but those which we have committed against God are great, and need such mercy as His only is. Take heed, therefore, lest for the slight and trivial sins against you, you shut out for yourself forgiveness from God for your very grievous sins.
If however any one thinks that he is not being burned when sinning, to him the Scripture saith, Shall a man wrap up fire in his bosom, and not burn his clothes? For sin burns the sinews of the soul, and breaks the spiritual bones of the mind, and darkens the light of the heart.
What can God do with one who willfully gives himself over to the world, and is deceived by its pleasures, or led astray by material wanderings? The man to whom He gives help is the one who turns away from material pleasures and from his former habits, who drags his mind at all times to the Lord, whether it will or not, who denies himself and seeks the Lord only. This is the man whom He keeps under His care: who guards himself on every side from the snares and entanglements of the material world, who works out his own salvation with fear and trembling, who passes with all heed amidst the snares and entanglements and lusts of this world, and seeks the help of the Lord, and hopes by His mercy to be saved through grace.
To uproot sin and the evil that is so imbedded in our sinning can be done only by divine power, for it is impossible and outside man's competence to uproot sin. To struggle, yes, to continue to fight, to inflict blows, and to receive setbacks is in your power. To uproot, however, belongs to God alone. If you could have done it on your own, what would have been the need for the coming of the Lord? For just as an eye cannot see without light, nor can one speak without a tongue, nor hear without ears, nor walk without feet, nor carry on works without hands, so you cannot be saved without Jesus nor enter into the Kingdom of Heaven.
Silence of lips is better and more wonderful than any edifying conversation. Strive to acquire humility and submissiveness. Never insist that anything should be according to your will, for this gives birth to anger. Do not judge or humiliate anyone, for this gives birth to anger. Do not judge or humiliate anyone, for this exhausts the heart and blinds the mind, and thereon leads to negligence and makes the heart unfeeling.
Leave off all evasions, bend your neck to humility and obedience, and you will receive mercy. If you practice with humility and obedience what you hear from the fathers, God will grant you His blessed help not only in the work you are doing, but will make all your works successful, for He protects the path of those who fear Him and watches their progress.
Whenever we enter the church and draw near to the heavenly mysteries, we ought to approach with all humility and fear, both because of the presence of the angelic powers and out of the reverence due to the sacred oblation; for as the Angels are said to have stood by the Lord's body when it lay in the tomb, so we must believe that they are present in the celebration of the Mysteries of His most sacred Body at the time of consecration.
Also in another place it shows that the angels are the ministers of the saints. For when Elijah was on the mountain and foreigners were rising up against him, his servant said, 'Many are coming against us and we are all alone.' Then Elijah answered, 'Do you not see the armies and multitudes of angels with us surrounding us to aid us?' (2 Kg. 6:15). You see how the Master and the multitude of angels are standing by the side of their servants.