From his exegesis of the Parable of the Narrow Door (Luke 13:22-30), in Kingdom, Grace, Judgment, Capon playfully restores a parable so often dripping in condemnation and proving back to its macroscopic continuity with the Gospel message. He starts off talking about its continuity with the story of the Mustard Seed (Luke 13:18-21):

One other observation about the mustard seed: it becomes a tree (dendron). I think it worth noting that the imagery of the tree is not only central to the shape of the Scripture but also inseparably involved with death. Mankind falls into sin and death by a tree in Genesis, is saved by a tree through the death of the Incarnate Lord on the cross, and live forever in Jerusalem in the shade of the tree of life that yields twelve fruits and whose leaves are for the healing of the nations. True enough, the Greek word for “tree” in these instances is xylon, not dendron: it means wood–originally, lumber or firewood. But in the later Greek of the New Testament, it quite plainly means “tree” (“xylon of life,” for example, Rev. 22:2); and from that usage, it easily becomes a metonym for the cross: Jesus “hung upon a xylon” (Acts 5:30) and “bore our sins on the xylon” (1 Pet. 2:24), etc.

…And so here it is. The narrow door–the tight squeeze in front of absolutely free salvation–is faith in Jesus’ death. Jesus does not set up ten thousand tricky wickets and threaten to admit to heaven only the aces who can negotiate every one of them. Jesus has simply put, smack in the front of his Father’s house of many mansions, the one, scant doorway of his death and ours. Its forbidding narrowness lies not in the fact that it is so small it is hard to find; rather it lies in the fact that it is so repulsive it is hard to accept…It lets in the riffraff, since all they have to be is dead; and it offends the classy, since they wouldn’t even be caught dead entertaining such a proposition.

Do you see what that does for the details of this parable? It abolishes the exclusivity of the imagery of narrowness and makes the parable susceptible of an inclusive interpretation. Watch. All the suction in the universe–all the “drawing” by which the Word woos creation back to be his bride–is through the narrow door of death. You may run from it, you may fight it, you may protest it, you may hate it–all in the name of what you call life. But if ever just once you slip up in your frantic struggle to live you way to your eternal home–if just once you simply drop dead–well then, ssssslurrrrp!!!…

…The nap out of which the householder/Christ-figure rises is Jesus’ three days in the tomb. The door he closes is the door to the exchanges of ordinary living. And the sleep to which he finally goes is the endless sabbath of the death of Jesus, which is the perpetual basis of the resurrection to eternal life.

And what, at that rate, is the narrow door the householder has still left open? Well, it is the remote possibility that, instead of noisily insisting on their own notions of living their way to salvation, they might just join him in the silence of his death and wait in faith for resurrection.