increase our faith
So todays’ Gospel, imho, should be read with a context of an immediate previous passage and taken in that context.
Luke 17:5-10 is mostly read in the context of doing great things with faith, or understanding the works of Kingdom of God, as similar passages suggest in Matthew, Mark and Luke:
The apostles said to the Lord, "Increase our faith." The Lord replied,
"If you have faith the size of a mustard seed, you would say to this mulberry tree, 'Be uprooted and planted in the sea,' and it would obey you.
"Who among you would say to your servant who has just come in from plowing or tending sheep in the field, 'Come here immediately and take your place at table'? Would he not rather say to him, 'Prepare something for me to eat. Put on your apron and wait on me while I eat and drink. You may eat and drink when I am finished'? Is he grateful to that servant because he did what was commanded? So should it be with you. When you have done all you have been commanded, say, 'We are unprofitable servants; we have done what we were obliged to do.'"
But if we read the very previous part of Luke, we enter the fuller context of what Jesus says:
Luke 17:1-4
He said to his disciples, “Things that cause sin will inevitably occur, but woe to the person through whom they occur. It would be better for him if a millstone were put around his neck and he be thrown into the sea than for him to cause one of these little ones to sin. Be on your guard! If your brother sins, rebuke him; and if he repents, forgive him. And if he wrongs you seven times in one day and returns to you seven times saying, ‘I am sorry,’ you should forgive him.”
Jesus starts with recognizing that offenders will come around but if they repent (prerequisite!), the offended or the hurt one should forgive.
Then you might think that the scene changes suddenly without any warning, there is no mention about changing the place or time. So we can assume that the continuity of the scene might be in place.
His disciples, hearing about forgiving every single time the repentant offender, ask Jesus to increase their faith because what he requires of them, ie, to forgive, is too difficult to do and imagine.
Jesus says that what is needed for that kind of forgiveness capacity is the faith of the size of the smallest seed found around Palestine. A mustard plant that shoots from this tiniest seed grows 10 feet tall and produces tons of seeds. He says that everyone has an access to that kind of faith. Everyone has the capacity to forgive a repentant offender.
And if relying on that size of faith, the strength of that kind of faith will be able to uproot a sycamore tree and it would obey the command.
Now, the sycamore (mulberry) tree had the longest and most spread roots. The tree was so hard to get rid of that people were specific about planting them not too close to walls and buildings bc it was impossible to uproot them and the roots would destroy the foundations of anything on its way.
The fruit of sycamore is plenty and most bitter of all fig trees around. You couldn’t even eat one bitter fig on its own in one sitting without adding other foods. And they were cheap.
Where does it go?
You do have faith to forgive repentant offenders, it is given to you. If you do, you uproot bitterness from your heart and you have the power to remove its roots and fruits from your heart. Tada! It’s all about forgiveness, preventing and denouncing roots of bitterness having the possibility of growing and spreading and bringing many bitter fruits.
“See to it that no one fails to obtain the grace of God; that no “root of bitterness” springs up and causes trouble, and by it many become defiled;” - Hebrews 12:15
The last part about an unprofitable servant I see as a reminder that forgiveness should be a norm. Because we have been forgiven much.