I am curious about the connection Jesus makes between fasting and New Wine. Many people relate it to the idea of appropriateness. It just strikes me as an odd comparison.
To understand the link between fasting and the parables Jesus gave in answer in Mark 2:18-22 (ESV), we need to note that the Mosaic Law prescribed only one fast on the Day of Atonement (Leviticus 16:29, 31). However, the legalistic Pharisees and the disciples of John the Baptist were following the traditions of men.
Now John’s disciples and the Pharisees were fasting. And people came and said to him, “Why do John’s disciples and the disciples of the Pharisees fast, but your disciples do not fast?” And Jesus said to them, “Can the wedding guests fast while the bridegroom is with them? As long as they have the bridegroom with them, they cannot fast. The days will come when the bridegroom is taken away from them, and then they will fast in that day. No one sews a piece of unshrunk cloth on an old garment. If he does, the patch tears away from it, the new from the old, and a worse tear is made. And no one puts new wine into old wineskins. If he does, the wine will burst the skins—and the wine is destroyed, and so are the skins. But new wine is for fresh wineskins.” (Mark 2:18-22 ESV)
The ESV Study Bible makes these comments:
Jesus refers to himself as the bridegroom, who in the O.T. was the Lord (cf. Isa. 62:5; Hos. 2:19-20). While Jesus is present with his disciples, they are to rejoice; when he is taken away from them, then they will fast.
Just as new, ushrunk cloth cannot coexist with an old garment, the kingdom of God cannot be regarded merely as a patch over the regulations of the Mosaic law and extra-biblical traditions. New wine vs. old wineskins illustrates the same truth – that Jesus brings a new era with new ways.
The reason it is inappropriate to put new wine into old wineskins is that the wine will burst the skins, destroying both the wine and the skins.
These two parables illustrate the fact that you can’t mix old religious rituals with new faith in Jesus. Jesus’ disciples were not fasting along with the Pharisees and John’s disciples because they were now under the new covenant of grace and faith in Christ.
Mark 2:21-22 is where we find the words about wine and wine skins.
Nobody sews a patch of unshrunk cloth on an old outer garment. If he does, the new piece pulls away from the old, and the tear becomes worse.
Also, no one puts new wine into old wineskins. If he does, the wine will burst the skins, and the wine is lost as well as the skins. But new wine is put into new wineskins.”
As always Jesus the master teacher uses illustrations that are readily understood by his audience. They understood what happens when fermenting wine stretches a wine skin. An old wineskin would have lost its flexibility so the fermentation process would cause them to burst open.
Having just been asked why his disciples did not practice fasting as did the Pharisees,Christ replied that, while he was with his followers, fasting as a sign of mourning was inappropriate. Then he said what is quoted above.
In this way Jesus helped them to appreciate that no one should expect his followers to conform to ritual fasting which was part of Judaism.
Christs powerful new teachings could not be contained in the system of Jewish religion. If one tried to it would be like putting new wine into old wine skins.
Instead those hearing and following Jesus could rejoice in the vitality of his teachings and not try to compromise them with the Pharisaical ways of the Jewish leaders.