Summary: A warning against mixing things that differ.
THE QUESTION OF FASTING.
It is a strange thing that the disciples of John the Baptist came to Jesus to ask, “Why do we and the Pharisees fast often, but your disciples do not fast?” (Matthew 9:14). It is unfortunately typical of religious people to be performing some ritual without actually knowing why they did it!
The only time when the Law COMMANDS fasting is in the ‘affliction of soul’ associated with the Day of Atonement (cf. Leviticus 16:29). This is apt, as it immediately associates fasting with repentance and forgiveness.
However, where the law commands just one fast per year, that on the Day of Atonement, the Pharisees would fast twice a week (cf. Luke 18:12). This would be on the market days, on Mondays and Thursdays, so that the hypocrites could strut around with their disfigured faces and draw the maximum amount of attention to themselves (cf. Matthew 6:16).
Yet a true fast will also lead the liberated person to seek relief and liberty for others. They will give bread to the hungry, shelter to the outcast, and clothes to the naked (cf. Isaiah 58:6-7). This is ‘pure religion and undefiled’ (cf. James 1:27).
The Pharisees’ ritual of fasting twice a week (cf. Luke 18:12) has nothing to commend it to those who are entering anew into a relationship with Jesus. And although the disciples of John the Baptist had cause enough to fast on account of the execution of their teacher, it was hardly appropriate to enforce fasting on those who were walking with the Lord during the time of His incarnation. He would be taken away from them soon enough, and THEN they would fast (Matthew 9:15)!
It is interesting that Jesus speaks here of Himself as the heavenly Bridegroom (Matthew 9:15). This is a role ascribed to God (Isaiah 62:5; Hosea 2:16), but also to the Lamb of God (Revelation 19:7; cf. Revelation 21:2). Jesus is doubtless the Bridegroom in Solomon’s Song of Songs.
Why would the Bridegroom’s friends mourn while He is with them (Matthew 9:15a)? Jesus is intimating His own death when He says, “But the days will come when the Bridegroom will be taken from them, and then they will fast” (Matthew 9:15b).
The two metaphors which Jesus introduces here, of a new patch on an old garment and of new wine in old wine-skins (Matthew 9:16-17) serve to warn us about mixing things that differ.
When we begin to follow Jesus, we enter into a whole new way of life. The problem in Samaria after the Assyrians had resettled the northern kingdom with non-Israelites, was that they sought to serve both their own gods AND the God of Israel (cf. 2 Kings 17:33, 2 Kings 17:41). That is to mix things that differ.
The problem in Galatia was similar, where men wanted to reconcile Judaism with Christianity by a painful compromise. To seek to superimpose our relationship with Jesus on top of even the best of ‘religious’ structures and strictures is to sew a piece of new cloth upon an old garment, or to store new wine in old wine-skins: it just will not work. Why would we even want to return into slavery to a law which has not redeemed us (cf. Galatians 3:3)?