Many Protestants avoid fasting, thinking it to be a vestige of Medieval asceticism that is somehow alien to Reformed piety.
The third example in this context concerns fasting that is not pretentious. A third time Jesus begins by denouncing the showy spirituality involved. In v. 16, he does not say fasting is wrong. He encourages it in v. 17. What is wrong is to wear a placard saying, “I’m humble; I’m fasting and suffering for God.”
This is what the hypocrites did. When the Pharisees of Jesus’ time fasted, they would appear in the marketplace with hair disheveled and clothes soiled and unkempt. Their appearance would loudly proclaim that they were fasting, and this fast was intended to be a sign of their superior piety. They wanted everyone to notice.
“What began as spiritual self-discipline was prostituted into an occasion for pompous self-righteousness. Some would wear glum and pained expressions on their faces, go about their business unwashed. . . and sprinkle ashes on their head, all to inform their peers that they were fasting. What was once a sign of humiliation became a sign of . . . self-righteous self-display.” (Carson)
But Jesus says, whenever you fast, don’t look downcast, somber, or deprived. For if you fast only to receive public acclaim, then sure enough you’ll have it, but that’s all the reward you’ll receive. That’s your payment in full.
On the contrary, as v. 17 teaches, you are to anoint your head as a sign of rejoicing. And you are to wash your face. Go on as normal, not seeking to draw attention to yourself. Verse 18 begins with a purpose clause, “so that.” Rather than the purpose of fasting being so that men will see, the true disciple fasts so that it will not be obvious or showy to men but obvious only to our Father who is unseen. Again, the omniscient Father is well able to reward this type of sincere worship.
So we have three examples of Jesus’ main point. Have you been examining your motives as we’ve proceeded? We should. Do you ever pray in any way to bring attention to your great piety or spirituality or maturity? Or do you pray with meaningless repetition? “Now I lay me down to sleep” may be fine for the child, but is the same prayer each time for an adult a sign of growth or retardation? Better be sincere and short and unpolished than eloquent and routine. Do you ever give and then tell about your generous giving to bring attention to yourself? Let us be careful and honest. When you fast, do you want everyone to know how dedicated you are?