Why should it use up the soil

Luke 13:1-21
But unless you repent, you too will all perish.  - don't think others are worse sinners than you.
A man planted in his vineyard and fig tree, if he hasn't found any fruits on it, Why should it use up the soil.  So as Christian can not has fruits, will be cut down.
Follow the laws is good, but essential is the love, so set free on the Sabbath day from what bound her is good thing. It is higher than the laws. God's law is made good to us.
Hypocrites! treat animal even better than a man.
The kingdom of God like the mustard seed and the yeast. It is small, but it will grow up huge when under right condition.
Why?
Roman troops had slaughtered some Galilean pilgrims in the Temple at Passover. People assumed that the victims of the two disasters must have been specially wicked, but that was not true. The whole nations is ripe for judgment and will meet an equally horrible fate if present opportunities for a change of heart are let slip.
Only Luke records the story of a woman who would be diagnosed by doctors today as suffering from a particularly crippling form of arthritis關節炎.
The gospel will preaching to whole of the world. So the kingdom of God will be here. It is not the work of man but it is God, man needs to prepare the works for gospel.
There is no one righteousness in this world. Everyone should repent and turn to Jesus.
How?
I have to prepare the work for kingdom of God, it is the Lord made mustard seed growing up, let the yeast bigger. If I do nothing why I received so much grace from the Lord?