Then the disciples came to Jesus in private and asked, “Why couldn’t we drive it out?” “He replied, “Because you have so little faith. I tell you the truth, if you have faith as small as a mustard seed, you can say to this mountain, ‘Move from here to there,’ and it will move. Nothing will be impossible for you.
When Jesus tells the disciples that they have “so little faith” it is not a matter of quantity since he explains in the next verse that even faith “as small as a mustard seed” can move mountains. Moving mountains is a proverbial expression for overcoming difficulties (see Isa. 40:4; 49:11; 54:10). The disciples must have had at least that much faith in some sense or they would not have tried to do the exorcism. Instead of referring to an inadequate amount of faith, Jesus is referring to a faith that is deficient. That is, it is not the kind of faith that is effective. This is clear from Jesus’ earlier words about an “unbelieving and perverse generation” (v. 17).1 An unbelieving generation is a faithless generation, which is what the disciples and the others were being at this time.
When I write about faith I usually say that biblical faith contains three elements: 1) the content of what must be believed, 2) assent to that content, and 3) trust in or commitment to Jesus Christ as the heart of the teaching. The third point (trust or commitment) is what makes faith personal and not just an intellectual or mechanical thing, and it is that personal element that was lacking here. It is why in Mark’s account Jesus tells the disciples that the reason they had failed to exorcise the demon was that they had not supported their efforts by prayer.
The problem was that they were approaching the challenge with a formula, expecting inevitable results, the sort of error expressed in the Latin phrase ex opere operato. It means that the results follow from the mere doing of the work, like Sacraments producing right results with or without faith, just because they are done. This is not biblical teaching. Neither the sacraments nor anything else achieves spiritual results mechanically since effective faith is a relationship in which we actually depend on God.
Here are two clear lessons from the story.
1. To be effective serving God we need a continuing relationship to God. It is always easy for a genuine experience of God’s grace and a genuine relationship to God to deteriorate into something merely mechanical. Because we had God’s blessing in the past we think that it will continue unchanged so long as we merely do the right things. We go to church. We read our Bibles. We even teach a class or preach sermons. But sadly we can do those and other worthwhile things without any real reliance on God, without true faith, and therefore fail badly. Nothing, however good in itself, can substitute for a personal, continuing, trusting relationship to God.
2. There are no shortcuts to spiritual authority. The disciples must have been seeking a shortcut when they came to the epileptic boy: do the right things, say the right words. But it did not work. What they needed to do was go back to Jesus to learn why they were failing and what they needed to go on. When they did this they grew, and the time came somewhat later, after Jesus had sent out a much larger number of disciples, that they returned to him with joy, saying, “Lord, even the demons submit to us in your name” (Luke 10:17). Just because you and I fail in a first effort now does not mean that our lives will always be characterized by failure.
1The words seem to be borrowed from Deuteronomy 32:5-20.