The reason that fasting has an effect on the spirits of evil rests in its powerful effect on our own spirit. A body subdued by fasting brings the human spirit freedom, strength, sobriety, purity, and keen discernment.
If the soul is vigilant and withdraws from all distraction and abandons its own will, then the spirit of God invades it and it can conceive because it is free to do so.
When we go to Confession, we enter Christ’s infirmary. Here God Himself is the Doctor, because only He can give and take away life, judge and acquit, punish and forgive. The priest is only a witness and a representative of God. That is why, standing visibly before the priest, and invisibly before Christ Himself, we must approach the great mystery of spiritual cleansing with great trembling! The priest hears our confession, but God accepts it. The priest examines our soul, but God will heal it. The priest will prescribe the remedies, but God will do the miracle of spiritual renewal.
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.
It's difficult to be saved in the world amidst the seductions and the customs of this world that go counter to the Holy Church. Evil communications corrupt good manners (I Cor. 15:33). It's difficult to be saved in the midst of dissolute society. In the Holy Scriptures it is said, With the holy man wilt thou be holy, and with the innocent man wilt thou be innocent. And with the elect man wilt thou be elect, and with the perverse wilt thou be perverse (Ps. 17:25-6).
St. John Climacus was asked if there are reliable signs by which it's possible to know whether a soul is drawing near to God or moving away from Him. After all, regarding ordinary things there are clear signs as to whether they're good or not. When, for instance, cabbage, meat or fish begins to rot, it's easy to notice it, since the rotting object begins to give off a foul odor, the color and taste change, and its external appearance witnesses to its deterioration. Well, and what about the soul? After all, it's bodiless and can't give off a bad smell or change its appearance. To this question the Holy Father replies, 'A sure sign of the deadening of the soul is the avoidance of church services.'
Those who have acquired genuine prayer experience an ineffable poverty of the spirit when they stand before the Lord, glorify and praise Him, confess to Him, or present to Him their entreaties. They feel as if they had turned to nothing, as if they did not exist. That is natural. For when he who is in prayer experiences the fullness of the divine presence, of Life Itself, of Life abundant and unfathomable, then his own life strikes him as a tiny drop in comparison to the boundless ocean. That is what the righteous and long-suffering Job felt as he attained the height of spiritual perfection. He felt himself to be dust and ashes; he felt that he was melting and vanishing as does snow when struck by the sun's burning rays (Job 42:6).
For the washing away of bodily dirtiness God has given water. And for the washing of spiritual foulness, God has given the grace of the holy Sacrament of Confession. Every man, when he dirties his hands, washes them. No one says, 'I will not wash my hands anymore, because I will get them dirty again!' But why is it then that many people say, 'I will not go to Confession, because I will not sin again tomorrow!' It is clear that the enemy of our salvation is enticing us not to wash our souls, so that he can gain power over them.
If Nabuzardan, the court cook of the King of the Babylonians, had not gone to Jerusalem, then the Temple would not have burned (cf. 2 Kings 24), That is to say, a person’s mind is not attacked by the flames of carnal pleasures, if a person is not conquered by gluttony.