A saint is not a non-sinner. A saint is a repentant sinner.
It is crucial that we distinguish, in our thought life and behavior, the difference between a sinner and a repentant sinner. To make this distinction is essential to our purification from the passions, illumination by the Holy Spirit, and deification by the same Holy Spirit in the likeness of Christ Jesus by grace.
In the Divine Liturgy, the proclamation is made that God has made “repentance the way of salvation.” Our salvation, to put it boldly, is not based on our moral perfection as much as it is on the way in which we respond to sin. (That, of course is not a reason to go on sinning that grace may abound. “God forbid,” to quote St. Paul in his letter to the Romans.)
The question is not whether or not I am a sinner. The question is, am I a repentant sinner?! If I am not repentant, do I desire to be a repentant sinner?! Do I understand myself to be in and consciously embrace the environment of the mercy of God?! Do I desire to do so?!
All of this wonderfully questions what we mean by “progress” in the Christian life.
It is necessary to distinguish a sinner from a penitent. If you have taken it upon yourself to rebuke a sinner, take care that you do not rebuke the penitent also. The Parable of the Prodigal Son demonstrates how dear a repentant sinner is to God. Therefore, let one who has become dear to God, be very dear to you. One time, a monk succumbed to sin, for which he was banished from his monastery. This monk went to St. Anthony, confessed his sin, repented, and remained with Anthony for a period of time. Then Anthony sent him back again to his monastery, but they did not receive him, and again drove him out. Again the penitent went to St. Anthony. Again, Anthony sent him back to the monastery, with a message to the fathers there: “A ship suffered shipwreck and lost its cargo, and only with great difficulty did that boat reach the harbor–and you want to sink even that which was saved from sinking!” Hearing this wise message, the fathers received the penitent brother into the monastery with joy. —St. Nikolai Velimirovich, The Prologue, July 30.
“Lord Jesus Christ, Son of God, have mercy on me a sinner. Grant me your grace to be a repentant sinner and not just a sinner in your sight.”