How often do you think fasting is mentioned in the Bible? By my count there are 77 biblical references to fasting. Does that surprise you? Despite so many references, fasting is not a frequent subject in pulpits, publications, or Christians' conversations.
This may be due to the typically private nature of fasting. Though it may be done cooperatively (as in Acts 13:2), fasting shouldn't be evident to others (Matthew 6:16-18). So it's possible that Christians around us fast more than we realize. But could the main reason that fasting is seldom taught be that fasting is seldom practiced? It is rather difficult for someone to advocate in a sermon or conversation a practice they don't observe.
Should Christians fast today?
The famine of teaching on the subject has led to a number of misunderstandings among believers about the discipline of fasting. One is that it is a practice relegated only to biblical times or religious eccentrics. But Jesus, when asked why His disciples never fasted, replied, "The days will come when the bridegroom is taken away from them, and then they will fast" (Matthew 9:15). Until the ascended bridegroom (Jesus) returns for His bride (the church), fasting is a spiritual discipline His disciples will occasionally practice. This was the understanding of Christians in the book of Acts who are reported fasting in 13:2 and 14:23. Church history reveals that since the days of the New Testament the followers of Jesus have likewise engaged in fasting.
Fasting and the gospel
Another frequent misconception about fasting is the failure to associate it with the gospel. The most egregious version of this is the belief that fasting can be a form of self-sacrifice that will impress God enough to open the door of heaven. That implies the life and death of Jesus is unnecessary. "Why repent and trust in Jesus? Just fast a little and Heaven is yours!" This is a great insult to the Father. Neither fasting, nor anything else we could do - no matter how painful, self-sacrificial, generous, or unselfish - can atone for our sins and reconcile us to God. Only Jesus, who offered Himself as a sinless sacrifice to bring others to God, can do that.
But it's also possible for genuine Christians to fast but fail to associate it with the gospel. They may fast, for example, simply in an effort to get things from God. In the New Testament, however, fasting is always related to the proclamation of God's grace or its fruit in believers' lives. Similarly, believers today should fast in a way that connects with the spread of the message of Jesus, or fast as one who is the servant of Jesus.
So a Christian might fast, for example, and connect it with prayer for missionary labors, for the Sunday-morning sermon, or their witness to a friend. He or she might also fast with prayer primarily for a personal concern, but rest their confidence that God would answer. The error on one side is failing to fast at all, and on the other is to fast with confidence in the work of fasting rather than the work of Christ.
Fasting for a biblical purpose
From the pragmatic perspective, the most common oversight is to fast without a clear biblical purpose. When you become aware of your hunger while fasting you often remember, "Oh, yeah - I'm hungry because I'm fasting." Your next thought should be something like, "And I'm fasting for this biblical purpose." There are at least 10 purposes in Scripture for fasting, but most relate somehow to prayer. So your hunger serves you during a fast in that it's a constant reminder of your biblical purpose.
Fasting must be a discipline, otherwise it's a blessing we'll never experience. When should you fast? Times of special need, guidance for an important decision, or especially intense spiritual longings may prompt you to enter into a fast. But Christians are free to experience the blessings of fasting as often as they desire.
How long should you fast? The Bible gives examples of fasts lasting from part of a day to 40 days, though the latter were likely supernaturally enabled. Today such a lengthy fast should probably be practiced with caution depending on your level of fitness or existing medical conditions. If you have any questions or health issues, seek medical counsel before you fast.
Fasting is a God-ordained expression of our belief that we have tasted and seen that the Lord is good (Psalm 34:8) - so good that there are times we're satisfied to feast on Him instead of the food that the Lord made to sustain us. Fasting is a temporary, physical demonstration that you believe the eternal, spiritual reality of the gospel, that "Man shall not live by bread alone, but by every word that comes from the mouth of God" (Matthew 4:4).
Do you believe that? Do you fast?