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.
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.
A thick rope is composed of thin strands of hemp. One thin strand cannot hold you bound nor strangle you, for you will easily, with the lightest touch, break it and free yourself. But if a thick rope binds you, you will stay bound, and it will strangle you. You cannot easily break it and free yourself of it. As a thick rope is made from thin, weak strands, so men's passions are made up of smaller initial sins. The small, initial sins a man can still break and free himself of. But sin on sin, repeated, the weave becomes thicker and thicker until it becomes a passion, which masters a man as only it can do. You can neither cut it out easily nor cast it away from you nor be divorced from it. Oh, when will men guard themselves from these first sins? Then they would not have so much difficulty in freeing themselves from the passions.
If the saints, who had attained passionlessless, had to be vigilant over themselves so as not to fall from their state of grace - then all the more is daily attentiveness and concern over our eternal salvation necessary for us sinners. The fact that we are still alive means that the Lord patiently endures our sins and awaits our amendment, and if someone lawfully labors for his salvation, the Lord takes him at a time when he becomes worthy of God’s mercy.
Smoke from wood kindling a fire troubles the eyes; but then the fire gives them light and gladdens them. Similarly, unceasing attentiveness is irksome; but when, invoked in prayer, Jesus draws near, He illumines the heart; for remembrance of Him confers on us spiritual enlightenment and the highest of all blessings.
Let us go forward with the heart completely attentive and the soul fully conscious. For if attentiveness and prayer are daily joined together, they become like Elias' fire-bearing chariot, raising us to heaven. What do I mean? A spiritual heaven, with sun, moon and stars, is formed in the blessed heart of one who has reach a state of watchfulness, or who strives to attain it.
Those who have sinned must not despair. Let that never be. For we are condemned not for the multitude of evils, but because we do not want to repent...
The soul of all practices in the Lord is vigilance. Without vigilance, all these practices are fruitless. He who is desirous of saving himself must so establish himself that he might remain continuously vigilant toward himself, not only in solitude, but also under conditions of distraction, into which he is sometimes unwillingly drawn by circumstances.
Now you become angry and fainthearted and grieved, thinking that the heavenly Father is slow in answering. But I tell you that this will also happen as you desire—it will definitely happen—but first it takes prayer with all your soul, and then you must wait. And when you have forgotten your request and have ceased asking for it, it will come to you as a reward for your patience and endurance. When you reach the verge of despair while praying and seeking, then the fulfillment of your request is near. Christ wants to heal some hidden passion within you, and this is why He delays in granting your request. If you obtain it sooner, when you demand it, your passion remains uncured within you. If you wait, you obtain your request and the cure of the passion. And then you rejoice exceedingly and give warm thanks to God Who arranges all things in wisdom and does everything for our benefit.
Watch constantly, learning to understand God's law, for this warms the heart with heavenly fire. Guard your lips from the idle word, or empty talk, lest the heart gets used to evil words.
Sin, to one who loves God, is nothing other than an arrow from the enemy in battle. The true Christian is a warrior fighting his way through the regiments of the unseen enemy to his heavenly homeland.
Apostolic teaching, Beloved, exhorts us that we put off the old man with his deeds (Eph. iv. 22; Col. iii. 9), and renew ourselves from day to day by a holy manner of life. For if we are the temple of God, and if the Holy Spirit is a Dweller in our souls, as the Apostle says: You are the temple of the living God (II Cor. vi. 16); we must then strive with all vigilance that the dwelling of our heart be not unworthy of so great a Guest.