Commentary on Luke 17:5-10

This week’s reading contains a couple of potentially difficult metaphors.

First, consider verse 6: “If you had faith the size of a mustard seed, you could say to this mulberry tree, ‘Be uprooted and planted in the sea,’ and it would obey you” (verse 6; see also Matthew 17:20; 21:21-22; Mark 11:22-24).

To be frank, I sometimes wish that Jesus had not said this! The maxim is so easily co-opted in support of crude theologies of faith. Especially when read literally, it can distort faith into a kind of magic. The problem is exacerbated by the fact that the example Jesus provides (“this mulberry tree”) seems random within the context of the Lukan narrative. Jesus apparently points to the nearest object and dreams up the most fantastic of scenarios. He could just as easily have said “turn this tree into a rabbit.”

Of course, Luke does not mean to conflate faith with magic. He is speaking in metaphor. But what the scholar and preacher find self-evident may not be so self-evident to people listening in the pews. This is a good opportunity to ask, What is faith, anyway? Or, less ambitiously for my purposes, What is the Lukan Jesus trying to say about faith in these verses?

At the very least, Jesus is saying that faith is not, fundamentally, something we quantify. Keep in mind that verse 6 is prompted by the apostles’ petition, “Increase our faith!” (verse 5). It is an understandable and well-intended request, especially when we consider what Jesus has just told them: “If the same person sins against you seven times a day, and turns back to you seven times and says, ‘I repent,’ you must forgive” (Luke 17:4). In other words, you do not stop offering forgiveness to the repentant sinner (the caveat of repentant sinner is noteworthy). Faced with such a teaching, who wouldn’t ask for “more” faith?

Jesus’ response suggests that the apostles’ request is misguided. He pivots from the question of quantity to the question of sufficiency. Faith “the size of a mustard seed” is sufficient for even the most demanding tasks of discipleship. The mustard seed was known both for its miniscule size (1-2 millimeters in diameter) and for the contrastingly large, unruly bush that it produced. It was therefore the perfect metaphor for small beginnings leading to big results. But again, the point of Jesus’ metaphor (now quite mixed) is not to quantify faith as much as to affirm its power. God works through a modicum of faith to empower us to forgive even the most annoyingly repetitive sinners.

In elaborating on this thought, Jesus introduces a second potentially problematic metaphor: the slave who works without expectation of special treatment (verses 7-10). The pitfall here is the implied association between discipleship and thankless drudgery: “Do you thank the slave for doing what was commanded?” (verse 9, in which the Greek syntax anticipates a negative answer). It is one thing to liken the disciple to the servant/slave who serves obeys his or her master (a common New Testament metaphor). But do we have to paint such a dismal picture? Are obedient disciples really just “worthless slaves” (verse 10a)?

Three observations help to alleviate the gloomy tenor of this metaphor. First, it makes more sense to translate the aforementioned phrase as “unworthy slaves” (an equally valid rendering of the Greek adjective achreios). This shifts the point of verse 10 from the seeming denigration of the disciple to the nature of discipleship itself. Obedience to Jesus is not, in and of itself, something to be rewarded (“we have only done what we ought to have done,” verse 10b). While the verses in question don’t put it this way, we could take them as an opportunity to explain how discipleship has its own rewards (fellowship with God and neighbor).

Second, we should keep in mind that scripture frequently connects obedience with joy (see Psalm 1:1-3; Psalm 119:111; 2 Corinthians 1:24; Hebrews 13:17). Especially when we conceive of obedience as an entering more deeply into fellowship with God, it is not hard to see how obedience even fosters joy. In fact, Luke is the preeminent spokesperson for joy in the New Testament. Numerous Lukan characters rejoice over God’s saving actions in and through the ministry of Jesus (Luke 1:14; 2:10; 10:17; 13:17; 15:5, 7, 10, 32; 19:6, 37; 24:52; Acts 5:41; 8:39; 11:23; 13:48, 52; 15:3, 31). Luke would be the last person to equate discipleship with drudgery.

Finally, we must bear in mind the previous verses: the apostles have asked Jesus to “increase our faith” (verse 5) in response to Jesus’ extraordinary directive about forgiveness (verses 3-4). Jesus, however, assures them that even a mustard-seed faith will prove sufficient (verse 6). Jesus then offers the slave metaphor as a way of situating his forgiveness directive among the everyday tasks of discipleship. What the apostles hear as an extraordinary case of discipleship is, in fact, quite ordinary. Forgiving the most repetitive (but repentant) sinner is more extraordinary than the slave tending the sheep or preparing dinner.

When it’s all said and done, then, this passage presents “faith” less in terms of our assent to Christological propositions (doctrine) and more in terms of our steadfast devotion to Christ—that is, as the Christian life itself. Numerous passages in Luke present faith (Greek pistis and cognates) in a similar way, often in the context of trials and temptations (Luke 8:12, 25; 12:42, 46; 16:10; 18:8; 19:17; 22:32) but only here with an emphasis on forgiveness (except perhaps Luke 16:10). Our ongoing commitment to the practice of forgiveness is, in other words, a reflection of our own faithfulness to Christ.

In a culture enamored by sensationalist news and highlight reels, it is easy to question our faith when it does not feel extraordinary. To be sure, there is nothing wrong with a mountaintop experience. But the most mundane act of faith carries extraordinary potential for transforming the world into the image of its Creator. I am reminded of the great Catholic saints of the mundane, André of Montreal (who worked as a monastery porter, sacristan, and launderer) and John the Gardener (who assisted his local monastery in gardening duties, including the altar flowers). By approaching each ordinary task as an opportunity to live their faith, they discovered the extraordinary depth of God’s love for them and for the seemingly ordinary (but quite extraordinary!) people around them.