Gospel (Lk 17:5-10)
The apostles said to the Lord, “Increase our faith!”
And the Lord said, “If you had faith as a grain of mustard seed, you could say to this sycamine tree, ‘Be rooted up, and be planted in the sea,’ and it would obey you.
“Will any one of you, who has a servant plowing or keeping sheep, say to him when he has come in from the field, ‘Come at once and sit down at table’? Will he not rather say to him, ‘Prepare supper for me, and gird yourself and serve me, till I eat and drink; and afterward you shall eat and drink’? Does he thank the servant because he did what was commanded? So you also, when you have done all that is commanded you, say, ‘We are unworthy servants; we have only done what was our duty.’”
This Gospel is clearly divided into two parts. In the first, Jesus speaks about the effective force of faith. In the second, he uses an example to teach us that faith, if it is true, needs to be shown in an attitude of unselfish service.
Jesus’ words about faith in the first part are analogous to those recorded by Matthew and Mark in their Gospels. There we are told that a person who has faith and does not doubt will be able to say to a mountain, “Be taken up and cast into the sea,” and the mountain will obey (cf. Mt 21:21 and Mk 11:22-24). Here we are told graphically that even faith like “a grain of mustard seed,” a tiny seed barely a millimeter in diameter, is enough to tell a sycamine (mulberry) tree, “Be rooted up, and be planted in the sea,” and it would obey. The mulberry is a large tree, with powerful and extensive roots, that is very difficult to root up, and impossible to make grow in water. The example of the mulberry tree, firmly anchored with strong roots, accords with the way Jesus begins his reply: “ If you had faith…” The word “faith” (in Hebrew ‘emunah) has the same root as the verb “to believe” (he’emin), which also means “to be firmly implanted,” “to have strength.” What Jesus wishes to express is quite clear: faith provides a strong support that enables one to face daunting challenges and imposing tasks that seem humanly impossible. For a person with faith, who relies trustingly on God, there is no obstacle that can’t be overcome. As Jesus will say on another occasion: “All things are possible for the one who believes” (Mk 9:23).
A basic requirement for a trusting faith that provides strength is humility, which implies the acknowledgement of one’s own weakness. God is the protagonist in salvation history and he invites us to collaborate as good servants of his. This is the topic of the second part of this Gospel passage. A person who serves others unselfishly, out of love for God, will be “helped by the knowledge that, in the end, we are only instruments in the Lord’s hands; and this knowledge frees us from the presumption of thinking that we alone are personally responsible for building a better world,” Benedict XVI says. “In all humility we will do what we can, and in all humility we will entrust the rest to the Lord. It is God who governs the world, not we. We offer him our service only to the extent that we can, and for as long as he grants us the strength.”
The example that Jesus sets forth in the second part of this Gospel passage, in a text found only in Luke, teaches us that faith and service cannot be separated, and that they are intimately united. A dedicated and self-sacrificing service, like that of the servant who after working all day returns home tired and hungry, but nevertheless prepares supper for his master, without complaining or thinking he was doing anything extraordinary.
It is certainly a demanding example that Jesus presents here. Today, one might expect this person to seek advice from a good employment lawyer about reclaiming his rights before such a master. But this total service that Jesus asks for is exactly what he himself carried out: “For even the Son of Man came not to be served but to serve, and to give his life as a ransom for many” (Mk 10:45). Faith works miracles—when it is shown in deeds of service, following the example of Jesus. Hence we are not called to serve in order to receive a reward, but to imitate God, who became a servant out of love for us.
Saint Josemaria, well aware that a faith shown in deeds of service is a supernatural gift that only God can infuse and intensify in the soul, once remarked: “every day, not just once but many times, I say this to him, I repeat the Apostles’ request: adauge nobis fidem! (Lk 17:5), increase our faith. And I add: spem, caritatem; increase our faith, hope and charity.”
 Benedict XVI, Encyclical Deus caritas est, no. 35.
 Saint Josemaria, Notes from a family get-together, 7 April 1974. Quoted by Javier Echevarría, Letter, 29 September 2012, no. 12.
The Gospel text is from the RSV Second Catholic Edition (RSV-2CE), copyright Ignatius Press.