"Then he told this parable: ‘A man had a fig tree planted in his vineyard; and he came looking for fruit on it and found none. So he said to the gardener, “See here! For three years I have come looking for fruit on this fig tree, and still I find none. Cut it down! Why should it be wasting the soil?” He replied, “Sir, let it alone for one more year, until I dig round it and put manure on it. If it bears fruit next year, well and good; but if not, you can cut it down”’ (Luke 13:6-9).
In Luke 13, Jesus is journeying through Samaria en route to Jerusalem. The people accompanying him were gossiping about some Galileans in Jerusalem who had died at the hands of Pilate (v. 1). Although it's not explicit in the text, Jesus believed that they were saying of those victims that they probably had it coming. Jesus challenges that assumption and tells the parable of the fig tree.
Perhaps because it arises out of current events, so to speak, it is one of the simplest of all his parables. In the parable we are all the fig trees, and God is the vinyard owner. I think perhaps Jesus sees himself as the gardner. We are all "planted" into this human experience to realize our true identity as Beings of Spirit, and to use that awareness to accomplish a specific spiritual purpose. If we are not "bearing fruit" by dedicating ourselves to that purpose, then we are useless in terms of Spirit; we will be removed from this human experience so that (I believe) we can recommit ourselves in Spirit and try again.
In the more familiar fig tree story in Matthew (21:18-20) and Mark (11:12-14), it is Jesus Christ who condemns the unproductive tree. The message, I think, is the same: If you're not serving your spiritual purpose, you will be removed from this mortal experience. This is not a judgment nor a punishment; it's rather a discernment that you are unproductive as a fig tree and may need to be "reassigned" in the Allness of the Divine.