Mark 2:18 Now John’s disciples and the Pharisees were fasting. So they came to Jesus and said, “Why do the disciples of John and the disciples of the Pharisees fast, but your disciples don’t fast?” 19 Jesus said to them, “The wedding guests cannot fast while the bridegroom is with them, can they? As long as they have the bridegroom with them they do not fast. 20 But the days are coming when the bridegroom will be taken from them, and at that time they will fast. NET
While fasting is a standard part of the spiritual practice of Jews in the first century, there is only one fast in the law (Yom Kippur – Day of Atonement). By the time the Jews return from Babylon, four additional days of fasting have been added (none of which were commanded by God). By the time of Jesus, the Jews are fasting twice a week. It is interesting that John’s disciples are fasting with the Pharisees as we normally don’t put these two groups together.
2Samuel 12: 14 Nonetheless, because you have treated the Lord with such contempt in this matter, the son who has been born to you will certainly die.” 15 Then Nathan went to his home. The Lord struck the child that Uriah’s wife had borne to David, and the child became very ill. 16 Then David prayed to God for the child and fasted. He would even go and spend the night lying on the ground. NET
Jonah 3:3 So Jonah went immediately to Nineveh, as the Lord had said. (Now Nineveh was an enormous city – it required three days to walk through it!) 4 When Jonah began to enter the city one day’s walk, he announced, “At the end of forty days, Nineveh will be overthrown!” 5 The people of Nineveh believed in God, and they declared a fast and put on sackcloth, from the greatest to the least of them. 6 When the news reached the king of Nineveh, he got up from his throne, took off his royal robe, put on sackcloth, and sat on ashes. 7 He issued a proclamation and said, “In Nineveh, by the decree of the king and his nobles: No human or animal, cattle or sheep, is to taste anything; they must not eat and they must not drink water. 8 Every person and animal must put on sackcloth and must cry earnestly to God, and everyone must turn from their evil way of living and from the violence that they do. 9 Who knows? Perhaps God might be willing to change his mind and relent and turn from His fierce anger so that we might not die.” 10 When God saw their actions – they turned from their evil way of living! – God relented concerning the judgment He had threatened them with and He did not destroy them. NET
There were three spiritual disciplines every Jew practiced to show their devotion. These three are prayer, alms giving and fasting.
Fasting can be a commemoration of a sad event (such as destruction of the Temple), for penance, for mourning or for spiritual reasons. This can get a little out of hand and create a spiritual problem if we think that we can fast and then God will do something for us. While acknowledging that we will pray, Jesus points out in the Sermon on the Mount that there is a right way and a wrong way to go about it. Same for the other two. The wrong way is to it in such a way that other people will notice how pious and religious you are.
The use of “bridegroom” is an unexpected metaphor on the part of Jesus. You don’t typically think about fasting at a wedding as they are filled with food and wine. (The first miracle Jesus performed was turning water into wine at a wedding). A first century Jew would understand this better than we do today as God entered into a “marriage” at Mt. Sinai and when His people turn away, their spiritual infidelity is compared to adultery. We are also told that the bridegroom is going away.
Hosea 2: 16 It will be in that day,” says the LORD, “that you will call me ‘my husband,’ and no longer call me ‘my master.’ … 18 In that day I will make a covenant for them with the animals of the field, and with the birds of the sky, and with the crawling creatures of the ground. I will break the bow, the sword, and the battle out of the land, and will make them lie down safely. 19 I will betroth you to me forever. Yes, I will betroth you to me in righteousness, in justice, in loving kindness, and in compassion. 20 I will even betroth you to me in faithfulness; and you shall know the LORD. 21 It will happen in that day, I will respond,” says the LORD, “I will respond to the heavens, and they will respond to the earth;….23 And I will sow her for myself in the land; and I will have compassion on No Compassion; and I will say to Not My People, ‘You are my people;’ and they will say, ‘My God.'” NHEB
God’s love is steadfast toward us knowing that at some point the unfaithfulness of His people will change.
We see the bridegroom theme in the New Testament as a reference to the Second Coming (see the Parable of the Ten Virgins in Matthew 25 and the Marriage Feast of the Lamb in Revelation 19). At that time, God will have kept his promise to Israel and will keep His covenant to us. The same is true to that alternate community of faith whose beliefs, whether political, economic or religious, stand in opposition to God. These are the people who ultimately love the things of the world and as a result, the Father’s love isn’t in them. (1John 2:15). https://biblehub.com/1_john/2-15.htm
Mark 2:21 No one sews a piece of unshrunk cloth on an old garment, or else the patch shrinks and the new tears away from the old, and a worse hole is made. 22 And no one puts new wine into old wineskins, or else the wine will burst the skins, and the wine is lost, and the skins will be destroyed; but they put new wine into fresh wineskins.” NHEB
New wine is unfermented grape juice that you place out into the sun and let it ferment. As it ferments, there are gases which cause the wineskin to expand. An old wineskin will explode under the pressure and you will be left without wine and wineskin. The point of these parables is that something new is happening and the old structures and rules will not apply. With that said, Jesus isn’t abolishing but fulfilling. He is building and finishing but for this to happen, there are some things that need to be corrected and some habits that need to be done away with.
“To attempt to engraft the living spiritual energy of the gospel upon the old legal ceremonial now about to pass away, would be as fatal a thing as to piece an old garment with new material, or to put new wine into old wineskins”. (Pulpit Commentary)