This is Part 4 of a 6-part series on biblical fasting.

Imagine fasting perfectly—skipping meals, spending time in prayer, following all the right steps—and yet displeasing God completely. It sounds impossible, doesn’t it? Surely if we’re doing the discipline correctly, God is pleased. But Scripture tells a different story, one that should stop us in our tracks and make us examine our hearts carefully.

The most sobering passage in all of Scripture about fasting comes from Isaiah 58. God’s people were fasting regularly. They were going through all the motions. And they couldn’t understand why God seemed unimpressed. Their complaint rings across the centuries: “Why have we fasted, and you see it not?” (Isaiah 58:3). The answer God gives is devastating—and essential for anyone who wants to practice this discipline faithfully.

Where We’ve Been

Over the past three weeks, we’ve established what biblical fasting is (voluntary abstinence from food for spiritual purposes, a means of grace that exposes dependencies) and why believers fast (humility, repentance, guidance, intercession, preparation). We’ve seen that fasting addresses heart-level issues, not just external behavior. Now we must confront a critical question: What makes fasting acceptable to God versus empty ritual?

This matters because it’s entirely possible to fast with wrong motives and gain nothing—or worse, to fast in a way that actually reveals the hardness of our hearts. The form can be perfect while the heart is far from God. That’s the danger Isaiah 58 exposes.

The People’s Complaint

“‘Why have we fasted, and you see it not? Why have we humbled ourselves, and you take no knowledge of it?’” (Isaiah 58:3a)

Listen to the indignation in their question. These weren’t people who were ignoring spiritual disciplines. They were fasting. They were “humbling themselves”—at least externally. They were doing what they thought they were supposed to do. And they expected God to notice, to respond, to be impressed.

This is the first warning sign: when we expect God to reward our fasting. Remember what we established in week one—fasting doesn’t earn God’s favor. We already have His favor in Christ. When we start thinking “I fasted, so God should…” we’ve already missed the point. Fasting isn’t a transaction where we pay with discipline and God pays with blessing.

The Israelites were treating fasting exactly that way. They saw it as leverage, as spiritual currency that obligated God to respond. Their fasting had become performance-based religion: “Look what we’ve done for You. Now what are You going to do for us?”

But God wasn’t impressed. And His answer reveals why.

God’s Indictment

“Behold, in the day of your fast you seek your own pleasure, and oppress all your workers. Behold, you fast only to quarrel and to fight and to hit with a wicked fist. Fasting like yours this day will not make your voice to be heard on high.” (Isaiah 58:3b-4)

Here’s what makes this passage so devastating: The problem wasn’t their fasting technique. It was their hearts. They were fasting while simultaneously:

Oppressing Workers

They withheld fair wages. They exploited people under their authority. They used their economic power to take advantage of the vulnerable. And then they fasted and expected God to bless them.

This exposes a terrible compartmentalization: treating spiritual disciplines as separate from how we treat people. As if we can fast on Tuesday and cheat employees on Wednesday and think God only cares about Tuesday. But God sees the whole picture. He’s not impressed by religious performance that exists alongside injustice.

Quarreling and Fighting

Their fasting didn’t lead to peace, gentleness, or love. It led to conflict. They were irritable, contentious, quick to argue. The “wicked fist” suggests they were even physically violent with each other.

Think about what that reveals. True fasting should make us more aware of our dependence on God and more humble toward others. If fasting makes you proud, judgmental, or angry—if you’re using your hunger as an excuse to lash out—you’ve completely missed the point. The external discipline has become a cover for internal ugliness.

Seeking Their Own Pleasure

Even while fasting, they were “seeking their own pleasure.” This is subtle but crucial. They weren’t truly seeking God—they were seeking what God could give them. They wanted the benefits of fasting (God’s attention, answered prayer, spiritual credibility) without the heart transformation.

This is perhaps the most common way fasting goes wrong. We’re not really after God Himself. We’re after what He can do for us. We want Him to fix our problem, grant our request, bless our ministry. The fast becomes a tool for getting what we want rather than an expression of wanting God.

The Fast God Chooses

After exposing false fasting, God describes what He actually desires:

“Is not this the fast that I choose: to loose the bonds of wickedness, to undo the straps of the yoke, to let the oppressed go free, and to break every yoke? Is it not to share your bread with the hungry and bring the homeless poor into your house; when you see the naked, to cover him, and not to hide yourself from your own flesh?” (Isaiah 58:6-7)

Notice God doesn’t say “Stop fasting.” He says “Fast this way instead.” True fasting, God says, flows naturally into justice and mercy. It creates compassion for others because it reminds us of our own need. When we experience hunger ourselves, we become more aware of those who are literally hungry. When we voluntarily embrace discomfort, we notice those who have no choice about their discomfort.

The fast God chooses doesn’t end when the meal ends. It continues into how you treat your workers, how you respond to the poor, how you share your resources. If your fasting doesn’t make you more generous, more just, more compassionate—it’s not biblical fasting. It’s just dieting with religious decoration.

This doesn’t mean fasting earns righteousness by leading to good works. Rather, genuine fasting—the kind that flows from a heart genuinely humbled before God—naturally produces fruit. Where there’s no fruit, there was no genuine humbling.

Jesus’ Warning

Centuries after Isaiah, Jesus gave a similar warning:

“And when you fast, do not look gloomy like the hypocrites, for they disfigure their faces that their fasting may be seen by others. Truly, I say to you, they have received their reward.” (Matthew 6:16)

The hypocrites Jesus describes were using fasting as a public display. They made sure everyone knew they were fasting. They looked miserable, disheveled, suffering—all so people would be impressed by their devotion.

Jesus’ response is sharp: they got exactly what they were after. They wanted human approval, and they got it. But that’s all they got. Their fasting went no deeper than the eyes watching them.

True fasting, Jesus says, should be practiced in secret. Anoint your head, wash your face, look normal. Let the fast be between you and your Father who sees what’s done in secret. If you’re broadcasting your fast—whether explicitly or through humble-bragging (“I’m just so hungry today because of my fast”)—you’ve turned it into performance for human consumption.

The Pharisee’s Fast

Luke’s Gospel gives us another sobering example:

“The Pharisee, standing by himself, prayed thus: ‘God, I thank you that I am not like other men, extortioners, unjust, adulterers, or even like this tax collector. I fast twice a week; I give tithes of all that I get.’” (Luke 18:11-12)

The Pharisee’s fasting was technically impeccable. Twice a week! Regular, consistent, disciplined. But look at what his fasting produced: pride and contempt for others. He used his spiritual disciplines to establish his superiority over “other men.” His fasting became a measuring stick for judging everyone else as inferior.

This is perhaps the most insidious form of false fasting: using it to feed spiritual pride. When you start thinking “I fast and they don’t, therefore I’m more devoted,” you’ve poisoned the entire practice. You’re no longer humbling yourself before God—you’re elevating yourself above others.

The Core Issue

What connects all these warnings—Isaiah 58, Matthew 6, Luke 18—is this: The issue isn’t the external practice but the condition of the heart. You can fast perfectly according to all the rules and miss the point entirely if your heart is:

• Using fasting as leverage with God
• Compartmentalizing spiritual disciplines from daily behavior
• Seeking benefits rather than seeking God Himself
• Performing for human approval
• Using fasting to establish superiority over others
• Harboring injustice while pursuing religious rituals

False fasting reveals hearts that are proud, self-righteous, hypocritical, and unchanged. True fasting reveals—and deepens—hearts that are humble, dependent, broken over sin, and hungry for God.

The Gospel Connection

Here’s what makes this passage both convicting and freeing: We can’t fix our hearts through fasting. Isaiah 58 exposes our hearts, but only the gospel repairs them.

If you read Isaiah 58 and realize “I’ve been fasting with wrong motives,” don’t try to fast better in your own strength. You’ll just produce a different kind of performance. Instead, return to the gospel. Remember that Christ fasted perfectly on your behalf. His righteousness covers your failed fasts, your mixed motives, your proud heart.

The gospel frees you from needing to use fasting to impress God (He’s already pleased with you in Christ) or impress others (their approval doesn’t determine your worth). You can fast from security, not to gain it. You can let fasting expose your hypocrisy because Christ’s perfect obedience has already been credited to you.

And here’s the beautiful paradox: when you stop trying to use fasting to earn righteousness, you’re finally free to practice it as it was meant to be practiced—as an expression of dependence on the One who is your righteousness.

Application Points

1. Examine your motives before fasting. Ask: Am I seeking God Himself or something I want Him to give me? Am I hoping He’ll be impressed? Am I planning to let anyone know I’m fasting? If yes to any of these, your motives need gospel realignment.
2. Look for fruit in your relationships. Does your fasting make you more patient with difficult people? More generous with resources? More aware of others’ needs? If fasting produces irritability, judgment, or pride, something’s wrong with your heart, not just your practice.
3. Check for compartmentalization. Are you fasting while harboring bitterness, ignoring injustice in your sphere, or mistreating people under your authority? God isn’t interested in spiritual disciplines divorced from how you treat your neighbor.
4. Respond to conviction with the gospel. When you recognize false motives or hypocritical fasting in your own life, don’t try harder to fast with pure motives. That’s just more performance. Instead, confess your need and rest in Christ’s perfect righteousness.
5. Let fasting flow into compassion. When you experience voluntary hunger, notice those experiencing involuntary hunger. Let your temporary discomfort make you more aware of others’ ongoing suffering. True fasting produces practical love.

Reflection Questions

• Are you fasting to seek God Himself, or to get something from Him? What would change if you were confident His favor doesn’t depend on your fasting?
• How does your fasting affect how you treat people around you—especially those under your authority or dependent on you?

Next week, we’ll move from warning to practical guidance. How do you actually fast biblically? What are the concrete steps for someone ready to try this discipline? We’ll make fasting accessible without making it easy, providing the practical wisdom you need to begin.

Until then, remember: God isn’t impressed by perfect external performance. He’s moved by hearts that genuinely depend on Him. And those hearts are produced by His grace, not by our fasting.