Summary: Fasting must be done so for the right reasons, and Jesus contrasts 1) Pretentious (Matthew 6:16) against 2) Proper Fasting (Matthew 6:17-18)
With the start of the Paralympics in Vancouver, one factor that has been stressed is the fact that the athletes competing should be considered as athletes just as much as their able bodied competitors who just finished. The Para Olympians train, and diet like their other Olympic cohorts. For many people their training and dieting is just as inspiring.
As Jesus has been talking about our training for the Kingdom, he now deals with fasting which is the third area-after those of giving (6:2–4) and praying (vv. 5–15)-for which Jesus gives a corrective to the hypocritical religious practices typified by the scribes and Pharisees. In each case the perversion of God’s standard was caused by the overriding desire to be seen and praised by others (v. 1). What we see here is the resumption of the pattern established in vv. 2–4 and 5–6 which is now resumed, with the third type of secret religious observance (France, R. T. (2007). The Gospel of Matthew. The New International Commentary on the New Testament (254). Grand Rapids, MI: Wm. B. Eerdmans Publication Co.)
The first two examples of Christian piety that Jesus gives in the middle of the Sermon on the Mount do not seem particularly difficult. To most people, prayer and ..giving .. make sense and are familiar, even though they may not understand them completely or practice them. But that cannot be said of Christ’s third example. Not only does fasting seem unnecessary to most persons, it may even seem quite foolish or absurd (Boice, J. M. (2002). The Sermon on the Mount : An expositional commentary (207). Grand Rapids, Mich.: Baker Books.).
Fasting has been practiced for various reasons throughout history. Many ancient pagans believed that demons could enter the body through food. When they felt they were under demonic attack they would fast to prevent more evil spirits from gaining access to their bodies. The yogis of most eastern religions and cults have always been committed to fasting-often for long periods of time, in which mystical visions and insights are claimed to be received. In modern western society fasting has become popular for purely physical and cosmetic reasons, and is recommended in some diet programs.
The Bible records no teaching or practice of fasting for practical reasons. Legitimate fasting always had a spiritual purpose and is never presented as having any value in and of itself.
During Old Testament times many faithful believers fasted-Moses, Samson, Samuel, Hannah, David, Elijah, Ezra, Nehemiah, Esther, Daniel, and many others. And the New Testament tells us of the fasting of Anna, John the Baptist and his disciples, Jesus, Paul, and numerous others. We know that many of the early church Fathers fasted, and that Luther, Calvin, Wesley, Whitefield, and many other outstanding Christian leaders have fasted.
But the only fast commanded in Scripture is the one connected with the Day of Atonement. On that day all the people were to “humble [their] souls” (Lev. 16:29; cf. 23:27), a Hebrew expression that included forsaking food as an act of self-denial.