At no place, in all his thirteen letters, does the apostle Paul command Christians to fast. Neither does Peter in his. Or John. Or any other book in the New Testament.

And yet, for two thousand years, Christians have fasted. One expression, among others, of healthy, vibrant Christians and churches has been the practice of fasting. However much it may seem to be a lost art today, fasting has endured, for two millennia, as a means of Christ’s ongoing grace for his church.

Why, then, if Christians, unlike Muslims, are not commanded to fast, do we still fast? First of all, Jesus’s teaching in the Gospels, particularly in Matthew, is plain enough. In addition to his own example (Matthew 4:2), and while not directly commanding his followers to fast, Jesus gave instructions for “when you fast,” not “if” (Matthew 6:16–17). More than that, in speaking about what his followers would do after his departure, he says, “then they will fast” (Matthew 9:15; also Mark 2:20; Luke 5:35). Again not a command, but a powerful promise from our Savior’s lips that we’d be foolish to ignore.

Early Christians Fasted

“When our painful sense of lack tempts us to focus on what we do not have, fasting now reminds us of what we do.”

Beyond Jesus’s own words, we find a pattern of fasting as the early church grows and multiplies in the book of Acts. In one of the most pivotal junctures in the story, the leaders in Antioch “were worshiping the Lord and fasting” to seek God’s guidance at a key moment in their church life (Acts 13:2–3). While they were doing so, the Holy Spirit spoke to them, “Set apart for me Barnabas and Saul for the work to which I have called them” (Acts 13:2). Then “after fasting [again] and praying they laid their hands on them and sent them off” (Acts 13:3).

Then Acts 14 provides us with a pattern of prayer and fasting “in every church.” As Paul and Barnabas revisited the cities in which they had made new converts on their first missionary journey, they “appointed elders for them in every church” and “with prayer and fasting they committed them to the Lord in whom they had believed” (Acts 14:23).

Why God’s People Fast

Overall, the New Testament may have little to say about fasting, but what it does say is important. And in what it doesn’t say, it leans heavily on the Old Testament. The Hebrew Scriptures do not speak the final word on fasting, but they are vital in preparing us to hear the final word from Christ. I count more than 25 mentions of fasting in the Old Testament, but it might be most helpful to look at three groups of passages with one common thread.

Inward: To Express Repentance

The first, most common, and perhaps most fundamental type of fast expresses repentance. Think of it as “inward.” God’s people realize their sin — typically not small indiscretions or lapses in judgment, but deep and prolonged rebellion — and come seeking his forgiveness.

For instance, in 1 Samuel 7, God’s people become freshly aware of their past and present idolatries (and God’s hand of discipline). They want to return to the Lord and newly “direct [their] heart to the Lord and serve him only” (1 Samuel 7:3). They assemble, under Samuel’s leadership, fast as a demonstration of their repentance, and confess, “We have sinned against the Lord” (1 Samuel 7:6). Similarly, in 1 Kings 21, even though king Ahab “sold himself to do what was evil in the sight of the Lord” (1 Kings 21:25), he “humbled himself” with fasting when confronted by the prophet Elijah — and God was pleased to delay impending disaster, even for such an evil king (1 Kings 21:29).

In Nehemiah 9, God’s people “assembled with fasting and in sackcloth” to confess their sins and seek God’s forgiveness (Nehemiah 9:1–2). In Daniel 9, the prophet realizes the time for the end of the exile has come. Daniel records, “I turned my face to the Lord God, seeking him by prayer and pleas for mercy with fasting and sackcloth and ashes” (Daniel 9:3). He “prayed to the Lord my God and made confession” (Daniel 9:4) for the sins of God’s people, in hopes of restoration. So also, Joel 1:14 and 2:12 call for fasts of repentance, to return to God from sin — as in Nineveh when the people believe the message Jonah reluctantly delivers. “They called for a fast and put on sackcloth, from the greatest of them to the least of them” (Jonah 3:5).

Old Testament saints often expressed an “inward” heart of repentance to God not only in words but with the exclamation point of fasting. Such fasts did not earn his forgiveness but demonstrated the genuineness of their contrition.

Outward: To Grieve Hard Providences

But fasting not only expresses repentance. On many occasions, it gives voice to mourning, grieving, or lamenting difficult providences. The seam that holds together 1 and 2 Samuel is the death of Saul and the nation’s ensuing grief. First Samuel ends with a seven-day fast of mourning for Saul (1 Samuel 31:13; also 1 Chronicles 10:12). As 2 Samuel begins, and news reaches David and his men, “they mourned and wept and fasted until evening for Saul and for Jonathan his son and for the people of the Lord and for the house of Israel, because they had fallen by the sword” (2 Samuel 1:12). It was not an expression of personal sin, but of grief at the death of their king.

When news of Haman’s edict arrives in Esther 4, “there was great mourning among the Jews, with fasting and weeping and lamenting, and many of them lay in sackcloth and ashes” (Esther 4:3). When David prays about his friends’ betrayal of him, he says they rejoice at his misfortune, even though he had “afflicted [him]self with fasting” and mourned when they were sick (Psalm 35:13–14). In Psalm 69, David says he “wept and humbled [his] soul with fasting” (Psalm 69:10), not because of his own sin, but because he was ill-treated. Similarly, Ezra “sat appalled” (Ezra 9:3–4), and fasted (Ezra 9:5), not at his own sin, but having learned “the holy race has mixed itself with the peoples of the lands” (Ezra 9:2).

Fasting gave voice to the pain and sorrow of sudden and severe “outward” circumstances and represented a heart of faith toward God in the midst of great tragedies.

Forward: To Seek God’s Favor

Finally, we find a kind of “forward” fast, not in response to sin within or grief without, but more proactive, in a sense, asking for God’s guidance or future favor. The first explicit mention of fasting in the Bible, coming at the sordid end of Judges, has this “forward” component. God’s people not only weep for the civil war unfolding among them but also inquire of the Lord for guidance (like Acts 13:2), whether or not to go out in battle against the tribe of Benjamin (Judges 20:26). We see such a “forward” orientation in 2 Chronicles 20:3: with a great multitude coming against his people, king Jehoshaphat sought the Lord and proclaimed a fast. He pled for God’s direction, “We do not know what to do, but our eyes are on you” (2 Chronicles 20:12).

David also sought God’s rescue on his knees “weak through fasting” (Psalm 109:24) and appealed for healing for his sick newborn with a forward-looking fast (2 Samuel 12:16, 21–23). “Who knows whether the Lord will be gracious to me, that the child may live?” (2 Samuel 12:22).

Fasting “forward” for God’s favor played a crucial role in the preservation and return of God’s people from exile. Before approaching the king to seek his favor, Esther sought God’s favor first, with a fast:

“Go, gather all the Jews to be found in Susa, and hold a fast on my behalf, and do not eat or drink for three days, night or day. I and my young women will also fast as you do. Then I will go to the king, though it is against the law, and if I perish, I perish.” (Esther 4:16)

God answered and, through Esther, saved his people.

Even Darius, king over Israel’s exile in its final stages, sought Daniel’s deliverance from the lions (in an often overlooked part of the story) with fasting (Daniel 6:18). Before setting out from Babylon, Ezra proclaimed a fast “that we might humble ourselves before our God, to seek from him a safe journey for ourselves, our children, and all our goods” (Ezra 8:21, 23). Also for Nehemiah (like 2 Chronicles 20:3), fasting not only expressed grief and mourning (Nehemiah 1:4) but led to seeking God’s favor: “O Lord, let your ear be attentive to the prayer of your servant, and to the prayer of your servants who delight to fear your name, and give success to your servant today” (Nehemiah 1:11). He prayed, and fasted. Then, in faith, he approached the king.

Fasting often served as an intensifier alongside “forward” prayers for God’s guidance, traveling mercies, and special favor.

Common Thread: Godward

This is not all the Old Testament has to say about fasting (for instance, see the correctives of Isaiah 58:3–6; Jeremiah 14:12; and Zechariah 7:5; 8:19), but the three general categories hold: fasting expresses (inward) repentance, grieves (outward) tragedies, or seeks God’s (forward) favor. And a common thread holds all true fasting together. Fasting, like prayer, is always Godward.

Faithful fasting, whatever the conditions of its origin, is rooted in human lack and need — for God. We need his help, his favor, his guidance. We need his rescue and comfort in trouble. We need his forgiveness and grace because we have sinned. We need God. He, not human circumstances or activity, is the common denominator of fasting. Fasting expresses to God our pointedly felt need for God. We have daily needs, and unusual ones. We pray for daily bread, and in times of special need, we reach for the prayer-amplifier called fasting.

Christian Fasting Is Unique

“In fasting, we confess we are not home yet, and remember we are not homeless.”

Christians have one final and essential piece to add: the depth and clarity and surety we now have in Christ. As we express to God our special needs for him — whether in repentance, or in grief, or for his favor — we do so with granite under our feet. When our painful sense of lack tempts us to focus on what we do not have, fasting now reminds us of what we do. Already God has come for us. Already Christ has died and risen. Already we are his by faith. Already we have his Spirit in us, through us, and for us. Already our future is secure. Already we have a true home.

In fasting, we confess we are not home yet, and remember that we are not homeless. In fasting, we cry out to our Groom, and remember that we have his covenant promises. In fasting, we confess our lack, and remember that the one with every resource has pledged his help in his perfect timing.

“Christian fasting is unique among all the fasting in the world,” says John Piper. “It is unique in that it expresses more than longing for Christ or hunger for Christ’s presence. It is a hunger that is rooted in, based on, an already present, experienced reality of Christ in history and in our hearts.”

In Christ, fasting is not just a Godward expression of our need. It is not just an admission that we are not full. Fasting is a statement — in the very midst of our need — that we are not empty.