This may be one of most frequently quoted-out-of-context scriptures in the New Testament! In a great many cases Luke 17:5 is quoted alone as it is above, with resulting problems of understanding. But what is the real significance of these words?
If we continue reading in Luke 17, we find that Jesus apparently did not accept the request of the disciples and even appears to gently rebuke them for the question. Unless we look at his words carefully, in context, they make little sense. Notice how Jesus replied to the disciples’request:
The apostles said to the Lord, “Increase our faith!” He replied, “If you have faith as small as a mustard seed, you can say to this mulberry tree, ‘Be uprooted and planted in the sea,’ and it will obey you. Suppose one of you has a servant plowing or looking after the sheep. Will he say to the servant when he comes in from the field, ‘Come along now and sit down to eat’? Won’t he rather say, ‘Prepare my supper, get yourself ready and wait on me while I eat and drink; after that you may eat and drink’? Will he thank the servant because he did what he was told to do? So you also, when you have done everything you were told to do, should say, ‘We are unworthy servants; we have only done our duty’” (Luke 17:5-10).
There is a clear negative note in what Jesus is saying here – in fact, Jesus not only denies the request, but he seems to be criticizing the request itself. To understand this reply, we should first notice that this exchange takes place well after Jesus had sent out his disciples to preach and heal and they had successfully accomplished many healings – which doubtless showed they had a measure of faith by this time (Luke 9:1-6 and see James 5:15). The disciples’ sudden request for more faith seems odd, therefore, if it is a general request. However, the immediate context of their petition throws more light on its meaning. Their request came directly after Jesus told them:
"… If your brother or sister sins against you, rebuke them; and if they repent, forgive them. Even if they sin against you seven times in a day and seven times come back to you saying ‘I repent,’ you must forgive them” (Luke 17:3-4).
So the request for greater faith appears to have been made in the context of doubt regarding being able to fulfill the seemingly extreme requirement of forgiving those that sin against us virtually without end. Understanding this makes more sense of Jesus’ reply. First Jesus apparently tells his disciples that forgiveness is not a matter of having more faith – faith is not really the issue here – and if they only have a small amount of faith, it will be enough. But then Jesus immediately switches to a parable-like story or example of the fact that servants must simply do what they are told and expected to do.
This story makes little sense if the disciples were requesting more faith in general, but it makes perfect sense if the disciples were essentially questioning their ability to forgive a repeated offense in an ongoing manner. Just as a servant continues to prepare his master’s meals on an ongoing daily basis, Christ seems to say, so the Christian must be willing to follow the instruction to forgive on an ongoing daily basis.
If the disciples had simply been asking for “more faith,” we would expect that Jesus would have responded in a positive manner – instructing them on developing faith, just as he instructed them when they asked him to teach them to pray (Matthew 6:9-13). But the specific things Jesus said and the apparent tone of his response indicate that the disciples were not as interested in growing spiritually in this instance as much as they were registering their opinion of the level of difficulty of the command they had just been given.
Jesus reminded the Twelve that faith was not really what was needed in this regard, but a simple understanding that the command to forgive was a command we are expected to follow. Ultimately, the disciples would come to learn that forgiveness is not based in faith, but in love. As Peter himself would later write: “Above all, love each other deeply, because love covers over a multitude of sins” (1 Peter 4:8).