Jesus spoke to his disciples about the inevitability that causes for stumbling or offense would come. Despite all the blessings associated with being his disciples and his trustworthy teaching and flawless example in showing love and compassion, there would come to be professing believers whose attitudes, words, or actions would deviate from the path of uprightness, wrecking the faith of others and leading them into sin. Jesus pronounced “woe,” grief, or distress for anyone through whom such stumbling would occur. (Luke 17:1)

The Son of God then stressed the serious consequences for stumbling others. It would be preferable for a person to have a millstone (a heavy one turned by a donkey, according to other manuscripts) hung around his neck and to be tossed into the sea than for him to cause one of the “little” or insignificant believers to stumble. Jesus’ words, “Watch yourselves,” likely mean to exercise care not to cause offense or spiritual injury to others. (Luke 17:2, 3) Another possibility is that the admonition, if linked to what follows, applies to being watchful about maintaining a forgiving spirit toward an erring brother.

The brother or fellow believer who sins against one should be reproved, with the objective being to aid him to see the error of his ways. If he repents, he should be forgiven. Even if he were to sin “seven times” (representative of a significant number of times) in a day and then each time came to the one against whom he had transgressed, asking to be forgiven, he should be forgiven all seven times. (Luke 17:3, 4)

When others repeatedly wrong us, we flawed humans find it hard to forgive. One is more likely to become distrustful and resentful. The apostles appear to have perceived that it would not be easy to heed Jesus’ admonition. This appears to have prompted them to request being granted more faith. Jesus then told them that, if they had faith comparable to a mustard seed (one of the smallest seeds with which they were familiar), they could command a mulberry tree to be uprooted and to be planted in the sea, and it would obey them. Thereby he illustrated that faith would enable them to surmount great obstacles, accomplishing the seemingly impossible. This would have included their being compassionate and forgiving when the usual response would have been one of anger and resentment. (Luke 17:5, 6)

Jesus then related a parable to illustrate the proper view toward the performance of godly service. Would anyone among them who had a servant that came to the house after having finished plowing or tending the flock say to him, “Come here immediately and recline” (to eat)? Instead, he would tell the servant to prepare a meal for him and to gird himself to serve, after which the servant could eat and drink. The owner would not feel obliged to his servant for having done what he was ordered to do. (Luke 17:7-9)

Applying the point of the parable, Jesus said, “Thus also you, when you have done all things you were ordered to do, say, ‘Useless slaves we are, [only] having done what we were obligated to do.’” (Luke 17:10) This strong language served to show the apostles that the performance of the labors entrusted to them was not to be the basis for pride or boasting. The carrying out of an assigned task is not in itself meritorious, and so it would not have been proper for the apostles to consider themselves as special. Instead, they were to regard themselves as would ordinary slaves who did nothing more than duty required and, from the standpoint of any special merit attaching to their deeds, could be called “useless.”