"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".
We have a problem here. Have you ever found someone with a small faith large enough to move grown trees around at will? If not, it may well be that there is no one with a faith as large as a small mustard seed. Or maybe we have not looked in the right place. Trees are being moved, we just haven't been watching. Or then again, maybe such faith only works on more important things like finding a parking space, success in business, passing an exam without study, ....... life in all its fullness type things.
Setting aside the improbable possibility that Jesus had psychotic anti-environmental delusions, we must ask, what is this tree moving faith? It could be a powerful psychic determination, a total concentration without doubt or waver. If its application works, then we obviously have it. If it doesn't work, then we obviously didn't have enough of it. Maybe we had enough of it, but we needed the assistance of others, but they didn't have enough of it.
So what's the problem here? It all stems from a failure to read the Bible properly. Consider what Jesus actually said. "If your brother sins, rebuke him, and if he repents, forgive him". The disciples were no fools. This command of Jesus was going to be a hard one to follow. So one of them responded by saying, "Increase our faith". Jesus then said those famous words. The point is simple enough. What Jesus commands can be done if we take him at his word - if we trust him, if we have faith. Even the smallest most ineffective trust in the commands and promises of Jesus will result in the commands and promises being achieved. Jesus was simply saying something like this, "Friends; it's not easy to forgive someone who has hurt you, but if they ask for your forgiveness, forgive them. And remember this, you can forgive them, for whatever I tell you to do can be done, even by someone whose dependence on me is as weak as a politician's logic".