The Ninevites believed God. A fast was proclaimed, and all of them, from the greatest to the least, put on sackcloth.
Jonah 3:5
Advent may not seem to be a time for sackcloth. For those who know the church calendar, it might seem more logical to think about repentance in Lent. But historically Advent and Lent used to be much more like each other than they are now, and it makes some sense that they would be. One of the images most associated with Advent is John the Baptist in the wilderness calling people to “prepare the way of the Lord”, and for John this meant repentance. We might think something similar as we imagine ourselves preparing to meet the baby King: approaching with a sense of unworthiness and contrition.
After the year we have had, we mostly want to skip the sackcloth and get straight to the celebration. Unlike Nineveh, we know the end to the story: God shows mercy and forgives. Why then do we need to go through with the sackcloth? Why not just rejoice? The truth is that rejoicing without repentance is entitlement. We focus on what we “deserve”, as though the world – even God – “owes us”. Certainly there’s a place for recognising that we need rest and need celebration, and God in His goodness gives us both. But He doesn’t owe us. Thinking that misses the point. Christians shouldn’t be surprised by grief and suffering in the world; we should know to expect it. What should surprise us is grace – not as though we keep forgetting the end of the story, but because it never fails to startle us with just how extraordinary it is.
Unless we know what it is to sit in sackcloth over sin, I don’t think we’ll grasp just how astonishing it is for God to lift us out of our ashes and invite us to meet His baby Son.
The Consolations of Writing 