There is a sin which is always 'unto death' [1 Jn 5:16]; the sin which we have not repented. Even a saint's prayers will not be heard for the unrepented sin. The person who repents correctly does not imagine that his sins are cancelled through his own effort; but knows that through this effort he makes peace with 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.
He who reveres the Lord does what is commanded, and if he commits some sin or disobeys Him, endures whatever he has to suffer for this as being his desert.
If the main goal of the repentant sinner should be total, light-bearing and blessed communion with God, then the main hindrance to this is the existence of the passions still active and working in him - the virtues being as yet unsealed in him - and the unrighteousness of his powers. Therefore his main work upon conversion and repentance should be the uprooting of the passions and sealing the virtues - in a word, correcting himself.
The Law (as it is written in the Scriptures) was given to us by Angels and, both before and after the days of the Law, Angels guided our illustrious forefathers to God, either by declaring to them what they should do and leading them from error and an evil life to the straight path of truth, or by making known to them the Divine Law, or in the manner of interpreters, by showing to them holy Hierarchies, or secret visions of super-mundane Mysteries, or certain divine prophecies. Now if anyone should say that God has shown Himself without intermediary to certain holy men, let him know beyond doubt, from the most Holy Scriptures, that no man has ever seen, nor shall see, the hidden Being of God; but God has shown himself, according to revelations which are fitting to God, to His faithful servants in holy visions adapted to the nature of the seer.
Set as a goal the kindling of the fire of the spirit, so that the spiritual fire will burn in your heart and, gathering up all your strength into one, will begin to build your inner man and finally burn up the tares of your sins and passions.
The root of good inner order is the fear of God. Preserve this fear within you constantly: it will hold everything taut, and will allow no slackness either in physical members or thoughts, creating a vigilant heart and a sober mind, and allowing no bodily torpor or blurring of thought. But one must always remember that success in any aspect of the spiritual life is the fruit of the grace of God. Spiritual life comes entirely from His most Holy Spirit. We have our own spirit but it is void of power. It begins to gain strength only when the grace of God flows in it.
In general, loquacity opens the doors of the soul, and the devout warmth of the heart at once escapes. Empty talk does the same, but even more so… Empty talk is the door to criticism and slander, the spreader of false rumors and opinions, the sower of discord and strife. It stifles the taste for mental work and almost always serves as a cover for the absence of sound knowledge…
The Lord commands all men to repent (Matt. 4:17), so that even the spiritual and those making progress should not neglect this injunction and fail to give attention to the smallest and most subtle errors.
Monasticism itself is a perpetual labor of conquering passions and uprooting them in order that, being in a pure and immaculate state, one may preserve oneself before the face of God. This, then, is your task! Give your attention to it, and direct all your powers towards it.
When tested by some trial you should try to find out not why or through whom it came, but only how to endure it gratefully, without distress or rancor.
Be attentive, my child, that you not judge any soul. For God steps aside from the one who judges his neighbor, and he falls, in order to learn to have sympathy for his sick brother.
My children, avoid criticism -- a very great sin. God is grieved whenever we criticize and loathe people. Let us concern ourselves only with our own faults -- for these let us feel pain; let us criticize ourselves and then we will find mercy and grace from God.