What is faith? The question is raised by the interaction between Jesus and the disciples, which comprises the short excerpt from Luke’s Gospel offered by the lectionary this coming Sunday (Luke 17:5–10). The disciples ask Jesus to increase their faith; Jesus, instead of responding with action, speaks back to them with a characteristic parabolic saying, about “faith the size of a mustard seed” (17:6).
The account that Luke provides is set during the long journey towards Jerusalem that Jesus began at 9:51, which continues until he enters the city riding on a colt (19:28–44). It introduces a series of incidents occurring in this last part of the journey in which faith is mentioned (17:5; 17:19; 18:8; 18:42). The sequence seems to come to a head when Jesus looks out over the city and weeps at their apparent lack of faith: “if you, even you, had only recognized on this day the things that make for peace! but now they are hidden from your eyes” (19:42).
This brief encounter, however, seems to be a Lukan redaction of an incident that Mark recounts after Jesus has entered the city (Mark 11:15), left the city (presumably for Bethany) for the evening (Mark 11:19), and then passed by a withered fig tree (Mark 11:20)—the same tree which Jesus had earlier cursed as the headed towards the city (Mark 11:12–14).
As Luke reworks the narrative he has inherited from Mark, he removes all reference to the fig tree and relocates the conversation to a place unknown, but certainly not within close distance of Jerusalem. The travelling group is still placed in “the region between Samaria and Galilee” at 17:11; some time later, they approach Jericho (18:35) and the tension mounts as they approach Jerusalem (19:11, 28) before finally arriving in the city (19:41, 45).
[Of course, if we were to try to harmonise Luke’s account with John’s Gospel, we would argue that Jesus and his companions had already visited Bethany—the meal in the house of Martha and Mary (Luke 10:38–42) would be at the same location where the brother of these sisters, Lazarus, died—in Bethany (John 11:1). Thus, he might well have already cursed the fig tree outside Bethany that is reported in a third Gospel (Mark 11:12–14). But we don’t engage in cross-Gospel harmonisation, forcing the evidence when it is lacking, do we? Just as well.]
So the Lukan redaction removes the fig tree, focusses the conversation on faith (Luke 17:5–6, a rewriting of Mark 11:22–23), and instead of the following instruction about prayer (“whatever you ask for in prayer, believe that you have received it, and it will be yours”, Mark 11:24) there is a parable about the role of a slave in a household (Luke 17:7–10).
In rewriting the saying of Jesus about faith, Luke deletes reference to the mountain (“if you say to this mountain, ‘Be taken up and thrown into the sea,’ and if you do not doubt in your heart, but believe that what you say will come to pass, it will be done for you”, Mark 11:23) with a saying in which a mustard seed is the key (“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”, Luke 17:6).
Being thrown into the sea remains a constant; the strange injunction to be thrown into the sea is spoken to a mulberry tree rather than a mountain. The mustard seed, introduced in Luke’s rewriting of the saying, is allegedly (but not actually) “the smallest of all seeds” (as is claimed at Mark 4:31—although this description is omitted in Luke’s version of the parable, Luke 13:18–19). The point still remains the same: just a little faith has such power contained within it.
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Luke has inherited stories from Mark in which Jesus commends people for their faith. He notes the faith of the friends of a paralysed man who is lowered through the roof of the house where Jesus is, in the hope that he might heal the man; in both stories, Jesus pronounces forgiveness when he sees the faith of the men and the paralysed man is then able to walk (Mark 2:1–12; Luke 5:17–26). He tells of a Jewish woman who had been suffering from hemorrhages for twelve years, with faith enough to believe that just a touch of the cloak of Jesus would make her well (Mark 5:25–34; Luke 8:43–48). He also tells of a blind man outside of Jericho who has faith enough to believe that just a cry of petition to Jesus would make him well (Mark 10:46:52; Luke 18:35–43). Both persons are told by Jesus, “your faith has saved you”.
Luke may also have known the story that Mark reports, of the anointing of Jesus by a woman during a meal (Mark 14:3–9). If he did know this, he has significantly reworked it; it takes place much earlier in his narrative (Luke 7:36–50), somewhere in Galilee rather than in Bethany, in the house of a Pharisee rather than the house of a leper, and it is his feet which are anointed, rather than his head. Another significant change is that, instead of memorialising the woman (“what she has done will be told in remembrance of her”, Mark 14:9), the scene ends with an affirmation by Jesus, “your faith has saved you; go in peace” (Luke 7:50).
A little before this scene, in his narrative order, Luke has told of the encounter between Jesus and a distressed centurion—or, rather, with some Jewish elders sent to Jesus by the centurion, whose slave was at the point of death (Luke 7:1–10). It’s a story told also in Matthew’s book of origins, and thus was likely to have been part of the so-called “sayings material” (Q) found in both of these Gospels, but not in Mark’s narrative. The request from the centurion to Jesus demonstrates the strong faith that this Gentile official has in the Jewish preacher and miracle worker (Matt 8:13); in Luke’s version, Jesus commends the Gentile with strong words: “not even in Israel have I found such faith” (7:9).
A similar commendation of another figure outside of Israel is offered by Jesus to the Samaritan, one of ten lepers who were healed by Jesus; when this man alone returns to offer his gratitude, Jesus, noting his status as “this foreigner”, commends him for his faith: “go on your way; your faith has made you well” (17:11–19).
So it is that a group of Galileean men, two Galileean woman, a Roman centurion, a Samaritan leper, and a blind Judaean man, are each commended by Jesus for their faith.
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In stark contrast is the collective group of disciples of Jesus, four times reprimanded for their comparatively poor expression of faith. First, in a boat that is being tossed on the waves by a fierce windstorm, Jesus confronts his panicking disciples, saying to them, “where is your faith?” (8:22–25).
In a later teaching session with them, on the ways that the natural world reflects the providential care of God (12:22–31), he injects a note of caustic judgement of his disciples: “if God so clothes the grass of the field, which is alive today and tomorrow is thrown into the oven, how much more will he clothe you—you of little faith!” (12:28).
Then, in a further extended teaching session with his disciples (17:20–18:34), as he offers a parable about a judge and a widow (18:1–8), he somewhat pessimistically concludes, “and yet, when the Son of Man comes, will he find faith on earth?” (18:8).
Finally, whilst gathered at table for what would turn out to be the final time before his arrest and trials (22:14–38), not so many words after he has commended the disciples for being “those who have stood by me in my trials” (22:28), Jesus upbraids Simon Peter for what he will do, not much later, around a fire in the courtyard of the high priest’s house (22:54–62). “Simon, Simon, listen!”, he pleads; “Satan has demanded to sift all of you like wheat, but I have prayed for you that your own faith may not fail; and you, when once you have turned back, strengthen your brothers” (22:42).
Faith appears to have been in short supply amongst the disciples, travelling with Jesus, listening regularly to his teachings, consistently observing his medical interventions—in contrast to those who encounter him but once, approaching with a trusting attitude, seeking his assistance; demonstrating faith.
It is no wonder that Jesus responds to the request of his disciples, “increase our faith!” with a somewhat barbed reply, “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” (17:5–6). The short parable about a slave (17:7–10) that follows this saying of Jesus is telling; the inference is that the disciples, still, despite everything, do not have such faith.
Just as the slave is expected to labour all day in the field and then undertake the required tasks in the house at night, before he eats and drinks, so the disciples are called to follow, listen, and obey, in diligence and humility; this is the kind of faith that they are required to have.
But do they have such faith? The inference that the disciples are lacking in this kind of faith is confirmed by the later declaration,matter still further teachings by Jesus, that “they understood nothing about all these things; in fact, what he said was hidden from them, and they did not grasp what was said” (18:34). The paradox that Luke sees running throughout the story of Jesus continues.
An Informed Faith 