John’s disciples and the Pharisees had a habit of fasting. Some people asked Jesus, “Why do John’s disciples and the Pharisees’ disciples fast, but yours don’t?”
Jesus said, “The wedding guests can’t fast while the groom is with them, can they? As long as they have the groom with them, they can’t fast. But the days will come when the groom will be taken away from them, and then they will fast.
“No one sews a piece of new, unshrunk cloth on old clothes; otherwise, the patch tears away from it, the new from the old, and makes a worse tear. No one pours new wine into old leather wineskins; otherwise, the wine would burst the wineskins and the wine would be lost and the wineskins destroyed. But new wine is for new wineskins.” (Mark 2:18–22 CEB)
There is a time for feasting, and there is a time for fasting.
These days not a lot of Christians in the Western world fast, but we need it as much as anybody. This is (at least in part) because our satiety dulls our sense of need. A little bit of intentional hunger can go a long way toward reminding us that we are mere finite creatures who can't take our lives for granted because we exist only by the grace of God. Fasting can also connect us in solidarity with the poor and the hungry.
Fasting is an act of negation - it's about not doing something, and it helps us to mark and remember other negations, other places of lack and emptiness: the emptinesses of material and spiritual poverty, the emptiness of mourning and death, the emptiness of sin and shame and war and violence and hunger. In marking and mourning these in fasting, we hope that we can begin to overcome these things, or minimally to be reminded of the God who promises ultimately one day to overcome these things.
But that brings up the important issue of timing. Fasting is a mournful way of engaging with the present time; feasting is a celebratory way of engaging with the present time. (The fact that we in Western civilization tend to avoid cultivating spaces for mourning and denial is certainly a sign of the poverty of our feasting, but that's another topic.)
From a Christian perspective, Lent is probably our most famous fast, while Christmas, Easter, Pentecost, and other occasions are examples of feast days. We could remix Qohelet here: there is a time for feasting, and there is a time for fasting.
John's disciples and the Pharisees lived in a time for fasting.
John came onto the scene dressing like an ancient near eastern mountain man and subsisting on a diet of insects and honey. His message was about repentance and expectation of God's kingdom. For John and his disciples, it was a time for fasting. They were interested in preparing the way, connecting with people in the midst of their brokenness and looking forward to God's future salvation.
The Pharisees were popular Jewish religious leaders who were also waiting for God's future salvation, albeit in a different mode. A part of that waiting for salvation included holiness, which they understood as a possibility for most anyone, not just some religious elite. Fasting was a part of that program of expectant holiness.
But Jesus and his disciples didn't live in a time for fasting; they lived in a time for feasting. They weren't waiting for God's salvation - that salvation was right there, in their midst, in the flesh of Jesus Christ as he inaugurated the reality of God's kingdom on earth. There's no need here for expectation or mourning. This thing is happening - the marriage of heaven and earth, God's permanent covenant in love with his people. And that's cause for a feast!
Fasting makes sense in the old order, but in Jesus all things are being made new. The new piece of cloth won't work as a patch for the old clothes - the way it shrinks in the wash will end up making the tear worse! And the old wineskins can't handle this new wine.
The implication might be that if you're in the old order, if you're living in the time for fasting, then you need an old patch to go with your old clothes. The old order and the old practice of fasting go together, they match - mourning and remembering lack and looking forward in expectation of fullness makes sense in the old order where that is the reality. But in Jesus this doesn't make sense. Jesus is a new piece of cloth, and he's here to create totally new clothes.
Similarly, the new wine of the kingdom of God won't work with the old order framework of fasting. The newness that Jesus embodies requires a new religious way of being. Fasting is an old skin, but new wine for new wineskins!
But our situation today is a little different. At one level Jesus is still with us, but at another we are still waiting for the fullness God's salvation - there is still, after all, hurt and pain and evil and death and violence and crying and fear where we live. We live between the already of God's kingdom, and the not yet. So sometimes we fast, because we're waiting. And sometimes we feast, because the New has truly arrived. But with Jesus, it’s always feast time.