'Moreover, when ye fast, be not, as the hypocrites, of a sad countenance: for they disfigure their faces, that they may appear unto men to fast. Verily I say unto you, They have their reward.17. But thou, when thou fastest, anoint thine head, and wash thy face; 18. That thou appear not unto men to fast, but unto thy Father which is in secret: and thy Father, which seeth in secret, shall reward thee openly.' -- MATT. vi.16-18.
Fasting has gone out of fashion now, but in Christ's time it went along with almsgiving and prayers, as a recognised expression of a religious life. The step from expression to ostentation is a short one, and the triple repetition here of almost the same words in regard to each of the three corruptions of religion, witnesses to our Lord's estimate of their commonness. We are exposed to them just as the Pharisees of His day were. If there is less fasting now than then, Christians still need to take care that they do not get up a certain 'sad countenance' for the sake of being seen of men, and because such is understood to be the proper thing for a religious man. They have to take care, too, not to parade the feelings, of which fasting used to be the expression, as, for instance, a sense of their own sinfulness, and sorrow for the nation's or the world's sins and sorrows. There are deep and sorrowful emotions in every real Christian heart, but the less the world is called in to see them, the purer and more blessed and purifying they will be. The man who has a sidelong eye to spectators in expressing his Christian (or any other) emotion, is very near being a hypocrite. Expressing emotion with reference to bystanders, is separated by a very thin line from feigning emotion. The sidelong glance will soon become a fixed gaze, seeing nothing else, and the purpose of fasting will slip out of sight. The man who only wishes to attract attention easily succeeds in that shabby aim, and has his reward, but misses all the true results, which are only capable of being realised when he who fasts is thinking of nothing but his own sin and his forgiving God.