Offense is coming. Problems will happen. People will sin. Woe to the one through whom it comes.
If you have faith you can uproot a mulberry tree and plant it in the sea. Why would you want to do that? Is Jesus saying that we will be able to do pointless things if we have faith? Or is he reasoning that, if faith will enable you to do something that difficult and unusual, that you will be able to do all that you need to do and more!
Don't look for extra thanks for doing what you are supposed to do!
One leper along returns to thank Jesus. It is very much like Jesus to point out that the leper that returned was a Samaritan. The least likely ones (lepers, and Samaritan lepers at that) are the ones Jesus delights to love and the Spirit delights to work in. Lord, make me grateful. Make me like that one.