If in the Old Testament the emphasis was especially on the sins committed with the deed, with the coming of Christ, we find that it is enough to think only of sin, and you have committed it. For the intention to sin departs from thought, and when we agree with sinful thoughts, we defile our soul, and our heart is no longer a pure abode of God. At the Last Judgment we will be judged not only by deeds but also by thoughts. Nothing created by God is bad, but our judgment is bad. The way we interpret things can be wrong. The mind is the power to make good or bad use of created things, says St. Maximus the Confessor. It is not the body that is guilty of sin, but our evil thoughts. Not the eye, but the mind and the thought that processes the image. The diligence of keeping our minds pure is one of the greatest spiritual needs that every human being is called to do in order to cleanse himself of passions and be saved. The fight against evil thoughts has been called the unseen war, which is a work of great finesse of the mind. It is the only means of cleansing the soul from sins, and especially from the known and unknown passions hidden in us. The struggle with thoughts is the first step in the spiritual ascent, say the Holy Fathers. We must guard against evil thoughts just as we must guard against evil deeds. For all evils have their source in evil thoughts, Origen said.
All sins knock at the door of the mind through thoughts
Through the thoughts the devil works in man, to push him to commit the deed. And the demons take the opportunity to arouse in us evil thoughts precisely from our passions, says St. John Chrysostom. Imagination is the place where sin enters the mind, says Saint Nicodemus the Aghiorite. He who does not sin with the mind will not sin with the deed either. If we want to turn away from sin, we must fight with thoughts, because passions have their roots in thoughts, and they continue to exist in the soul even when we do not commit evil deeds. Saint John Chrysostom says that the evil thoughts that have settled in our souls are constantly at war inside us. And the evils within are more terrible than those that come to us from without. The soul must not be afraid of the races of the world, but of the diseases which he himself has brought upon himself. How can we fight bad thoughts?
By contemplating the holy, the commandments of Christ the Savior, and especially by replacing bad thoughts with good thoughts. Let us always have in our minds, on our lips and in our hearts a good word and a good thought for all those around us, but also for all the events that come to us. In this way we will cleanse our souls and preserve the health of our minds. A clean and good thought will always bring us closer to God.