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.
When you receive from Heaven the gift of patience, be attentive and vigilant over yourself, so as to hold and keep within yourself the grace of God, lest sin should creep unnoticed into your soul or body and drive away this grace.
We must accomplish the course of our earthly pilgrimage with the greatest attention and watchfulness over ourselves, unceasingly calling upon God in prayer for help.
He who wants to cross the spiritual sea is long-suffering, humble, vigilant and self-controlled. If he impetuously embarks on it without these four virtues, he agitates his heart, but cannot cross.
The view we take of our Savior's dispensation is the view of the holy fathers who preceded us. By reading their works we equip our own mind to follow them and to introduce no innovation into Orthodoxy.