Matthew 17:20Meaning & Commentary from the Church Fathers

Contemplate the advantages that arise from these two virtues. A person who prays appropriately and simultaneously fasts has very few needs; those who require little are not consumed by greed, and those free from greed are generous givers. A person who observes fasting becomes light and cheerful, able to pray with a joyful spirit, subdues sinful desires, earns God's favor, and humbles their proud heart. This is why the apostles consistently practiced fasting.

One who prays while fasting possesses wings, lighter than the very wind. Such an individual does not fall into lethargy, doesn’t talk excessively, doesn’t yawn, or grow lax in their prayers, as often happens with many; instead, they soar like fire and rise above the earth, becoming a formidable adversary against demons, for there is no stronger individual than one who prays with sincerity. If a woman can humble a tyrant who shows no fear of God or shame before others, how much more can one who stands continuously before God, exercises self-control, and renounces physical indulgences invoke His mercy? If your body lacks the strength for continuous fasting, know that it can still engage in prayer and refrain from indulgence in bodily pleasures. If fasting proves difficult, at least avoid overindulgence; this act is significant and is not far removed from fasting, and it can subdue the frenzy of evil. Indeed, there is no more favorable environment for demons than indulgence and drunkenness, the root and source of all iniquity. By this very means, the devil led the Israelites into worshiping idols, and it ignited the sinful passions of the people of Sodom. As Scripture notes, “this was the iniquity of Sodom thy sister and her daughters: in pride, satiety, and idleness” (Ezekiel 16:49). In a similar way, he has led many others to destruction and to eternal damnation. Truly, what calamity does not stem from indulgence? It degrades humanity to the level of pigs, and even worse. A pig may wallow in muck and consume waste, yet a glutton revels in preparing the most loathsome feast, devising illicit relationships and immoral desires. Such a person mirrors the state of one possessed by demons; they exhibit the same shamelessness and aggression. While we may feel pity for the demon-possessed, such indulgent individuals inspire revulsion and hatred within us. Why is this? Because they rage uncontrollably, transforming their bodies into vessels of filth and moral decay. When we examine the inner self of such a person, we find a soul that is frozen and numb, akin to what one experiences in the harshest winter, rendered incapable of assisting their vessel due to overwhelming depravity.

The Lord responded, "This kind can come out by nothing but prayer and fasting." Here we find the profound significance of fasting combined with prayer. It seems that when He bestowed the ability to cast out unclean spirits and heal ailments, He did not immediately require His apostles to fast in His presence, leaving such observance for the time of His impending Passion. Can the sons of the bridal feast fast while the bridegroom is with them? But the days will come when the bridegroom is taken away from them, and then they will fast in those days (Luke 5:34). It is clear that the apostles performed miracles not through intense fasting or extended prayer but by simply commanding in the name of Christ, relying on the authority they had been granted, and their commands were fulfilled. However, the strength of the evil spirit afflicting the mute man was formidable, necessitating the utmost level of grace and power to overcome it. The only means to achieve such blessed and effective power could be through faith, which was already active in the apostles. The Lord advocates for prayer and fasting, indicating that this kind of strength cannot be attained through any other means than through these practices. Can we not recognize the crucial nature of combining fasting with prayer? The apostles needed it; do we not find ourselves in need of it as well? Those who perform miracles require it too; can we afford to disregard such assistance? It plays a vital role in triumphing over the oppressive and dominant forces of evil: is it not essential in subduing the desires of the flesh that oppose the spirit?

Is it unreasonable to conclude that where fasting and prayer are absent, demons may reside? It is plausible. Demons inhabiting a person often conceal their presence, subtly guiding their host towards all manner of wickedness and away from the good, leading them to believe they are acting of their own accord while actually executing their enemy's designs. However, the moment one dedicates themselves to prayer and fasting, the enemy retreats, biding its time for an opportunity to return, which it does as soon as prayer and fasting are neglected.

Furthermore, we should be committed to daily fasting, watchfulness, and sober prayer, primarily focusing inwardly. Constant prayer and a vigilant mindset act as sentinels that guard our spiritual treasures, our minds, and our service to God from being ravaged by demons, empowering individuals to devote themselves to divine service. Once an individual’s mind and soul are cleansed, deceptive dreams cease. Before purification, all dreams are rooted in demonic deceit, no matter how accurate they may appear. Prayer and fasting serve as defenses against demonic influence within us.

Prayer, likened to a breath of grace, purifies the spirit, fills the mind with enlightenment, and instills diligence in the believer. Prayer, when paired with mindfulness, safeguards the soul, extinguishing forgetfulness much like water quenches fire. This virtue merits the title of beautiful light due to the illumination it brings. Through love for prayer, one can transform from sinful, unworthy, and vile into holy and gracious; from unwise and foolish into wise and astute; and from unjust and harsh into righteous and merciful. Moreover, it enables you to become contemplators of divine mysteries, theologians, and seers, through the invocation of the name of the Lord Jesus Christ, the Son of God. Many holy fathers have affirmed that the Jesus Prayer is the source of all blessings and a treasure of virtues, quickly granting individuals the grace of the Holy Spirit and leading to salvation. It unveils the hidden, offers discernment, and provides guidance.

Just as one sees their reflection in a mirror, through vigilant and vigorous prayer a person discerns the state of their life—is it lived righteously or poorly? This focused prayer eradicates the shadows of passions, liberates from all demonic snares, and conquers thoughts, words, and actions of evil. It recognizes all visions and obsessions of malice and overcomes all natural desires, feelings, and sufferings. It assists and purifies in every demonic temptation. Like a fiery sword, it cleaves through; for it is God, before Whom all things retreat. No other force can vanquish demons and their deceptions except for vigilant and frequent Jesus prayer, grounded in a clear mind and humility. Without guidance in this Jesus prayer, holy fathers contend that a person struggles and may suffer, grasping its significance without knowing the proper execution in accordance with its depth.

Misguidedly believing they have attained perfection, such individuals may become absorbed in dreams while harboring internal adversaries, failing to cleanse their soul and mind of passions tied to sobriety, focus on the heart, and guarding the senses. Those who do so are woefully overtaken by demons. When commencing this virtuous endeavor, one must first temper the passions. Next, they should refrain from actions displeasing to God. Furthermore, they must never do to a brother what they would themselves not wish to experience. Additionally, they should guard their mind against impure thoughts and temptations. Lastly, one must protect their heart from lust and immorality. This sobriety of mind and heart requires vigilance and humility to safeguard one’s thoughts and emotions.

Moreover, restraining the desires of the flesh—through hunger and thirst—helps to shield the heart from lustful distractions and fosters the strength of prayer, overpowering and annihilating numerous passions and evil spirits. Grace flourishes within a person, as fasting and the Jesus Prayer embody the disciplines of restraint, purification, and strengthening that aid in keeping the heart sober. Sobriety itself is the foundation of praise and holiness; it entails purity of mind, heart, and soul—their clarity and transparency. The uncleanness of mind manifests in harmful thoughts and passions, while the heart's impurity leads to a craving for lust and immorality. Then, the soul's impurity is associated with mental passions, and the body’s impurity correlates to physical desires.

One cannot maintain a pure heart or avoid defilement if the flesh is not subdued through fasting and other ascetic disciplines. It is impossible for a priest to fulfill their role without fasting and other ascetic practices. Without spiritual efforts, the flesh will not submit to the spirit for holy work. Likewise, prayer does not ascend nor thrive without the mortification of the flesh, as natural needs and bodily health can impede us, kindling the flesh’s desires. Decay breeds unclean thoughts that corrupt the mind, leading both heart and body toward sensuality. The lustful inclinations of thoughts and heart lead to the corruption of soul and body, resulting in the departure of grace from individuals, emboldening evil spirits to possess them and manipulate the flesh and soul into passions.

These spirits can influence the mind toward distraction and oblivion, ultimately leading one into sinful temptation. Let us consistently uphold fasting, discipline, and spiritual labor as a refuge from demonic oppression and mental captivity. Fasting purifies the body, nourishes, strengthens, and empowers prayer. Like flame rising from fire, fasting and mindful prayer ascend, scorching demons so that they cannot approach, similar to a burning furnace, nor can they inflict harm upon a pure soul and sober body. To our God be glory always, now and forever, unto ages of ages.

One who prays while fasting possesses two wings, lighter than the wind.

Saint Philaret, Metropolitan of Moscow, emphasizes the necessity and benefits of combining fasting with prayer, asserting that if the Apostles required this practice, surely we do as well. Miracle-workers find assistance through it; can we afford to overlook such aid? It contributes to triumph over the tormenting and overpowering spirits of evil; will it not also aid in subduing the flesh, which battles against the spirit? Blessed Jerome illustrates that “he who rages at new moons” symbolizes an individual who occasionally succumbs to various vices, at times falling into the sin of adultery, and then into those depths contrary to divine love. Thus, every sinner overtaken by passion is, in a spiritual sense, akin to a demon-possessed person who needs healing, and this restoration of the soul from passions cannot occur without fasting and prayer. When interpreting the Lord's reference to “this generation,” scholars highlight the varying degrees among evil spirits, just as there exists a hierarchy among angels in heaven; likewise, evil spirits also have ranks, with some being more powerful than others.

Relating this to verse 20, we can summarize Jesus Christ's statement as follows: “If your faith is genuine and true, even if it is small, you will accomplish remarkable feats that appear impossible; however, to drive out these specific evil spirits, you must possess a level of faith that can only be reached through prayer and fasting; and in this instance, such faith was lacking.” You might ask, if faith is essential, what role does fasting play? Fasting, in conjunction with faith, grants immense strength, imparting wisdom and transforming a person into a being akin to an angel, fortifying them against spiritual adversaries. Yet, this alone is insufficient; prayer is also crucial. A person who fasts becomes light and uplifted, praying with joy... Those who pray with fasting soar like the wind, swift as fire and above the earth, thus becoming formidable foes against demons, as there is no stronger individual than one who prays sincerely.