How does fasting prepare us for spiritual warfare?

In the temptation on the mountain in the wilderness, Christ our Commander in war fasted (Matt. 4:1–2) that we may imitate Him, being His faithful soldiers. He is our perfect model and leader, who trains us to fast while fixing our gaze on our Commander who fasted and confounded Satan and his kingdom. The Fathers knew that the fasts of the Church are the seasons of the most intense demonic warfare. In their discriminating spiritual understanding, they took this to be a sign of the terror that those who truly fast instill in demons.

St. Augustine says, “When the tempter intensifies his warfare, we must fast so that the body may fulfil its Christian duty in striving against the desires of the world through repentance, urging the soul to conquer in humility.”

419 St. Gregory of Nyssa, On the Making of Man 18.9 (NPNF II/5:408).

420 St. Basil of Caesarea, On Fasting and Feasts 1.4 (PP 50:57).

421 St. Jerome, Against Jovinianus 2.15 (NPNF II/6:399) amended.

422 St. Philoxenus of Mabbug, The Discourses of Philoxenus of Mabbug: A New Translation and Introduction trans., Robert A. Kitchen (Collegeville, Minnesota: Liturgical Press, 2013) 11.25, 32 (440, 446): pp. 343, 348.

St. John Saba says, “Do not overfill your belly, lest fornication torture you. Do not greatly weaken your body, lest your enemy make you weary. Hold to a rule and, behold, henceforth you will go forward on the royal way and your journey will be without fear.”⁴²³

St. Cyril says, “‘He afterwards hungered,’ because, on the other hand, it was necessary that He Who refused not our poverty should withdraw from nothing whatsoever that belongs to man’s condition, He consented for His flesh to require its natural supplies; and hence the words, ‘He hungered.’”⁴²⁴

St. Isaac the Syrian says, “all strife against sin and its desires is to be preceded by the labour of fasting, especially if one is combating inward sin.”⁴²⁵ He again says, “And also our Saviour, when He manifested Himself to the world at the Jordan, began from that point. For when He had been baptised, the spirit led Him into the wilderness, and then He fasted forty days and forty nights. And all those who follow His steps, base the beginning of their struggle upon this action. That weapon was polished by God, who should despise it without being blameworthy? If the lawgiver has fasted, to which guardian of the law is it not necessary to do likewise?”⁴²⁶

St. John of Thebes says, “Bodily fasting is abstinence from food, but spiritual fasting is hunger and thirst for righteousness.”

St. Jerome says, “After you have paid the most careful attention to your thoughts, you must then put on the armour of fasting and sing with David: ‘I chastened my soul with fasting,’ (Ps. 69:10) and ‘I have eaten ashes like bread,’ (Ps. 102:9) … Eve was expelled from paradise because she had eaten of the forbidden fruit. Elijah on the other hand after forty days of fasting was carried in a fiery chariot into heaven … and in Job it is written of behemoth that ‘his strength is in his loins, and his force is in the navel of his belly’ (Job 40:16).”⁴²⁷