Plants

"He replied, 'Sir, let it alone for one more year, until I dig around it and put manure on it. If it bears fruit next year, well and good; but if not, you can cut it down.'" (Luke 13:8-9)
Jesus has come down into our lives to put in new fertilizer and other vitamins so that we can grow and bear fruits.  The only way we can bear fruits is by taking all that Jesus teaches us in and applying it in our lives.  In this parable, in particular, Jesus mentions that we are given a chance to become better.  In fact, God is always working within us to make us better.  When we allow God to dictate what happens in our lives, we will grow to bear great fruit.
Another note is that Jesus preaches against judging.  Therefore, He considers this to be of such a great importance, for He speaks of it before teaching us that we need to live in Him.  Thus, by making peace with our neighbors and becoming a unified family of God, we shall live and breathe the gospel.