Luke 13:1-9; interpreting the parable of the barren fig tree

I received the following question from Warren Wilson, a reader of The Surprising God. I invite other readers to help me reply.

(public domain via Wikimedia Commons)

Luke 13:1-9 gives the parable of the barren fig tree. Obviously, we can understand our Lord's emphasis on repentance as encouragement for us to subjectively awaken to the salvation that is already ours through his life, death, resurrection and ascension. My question has to do with the apparent urgency with which he speaks. It has a now or never tone to it. "Better repent now because you don't know how much time you have." It gives the impression that they're excluded unless they repent.

I've looked at what Robert Farrar Capon has to say about this parable and it is not satisfactory. While he does remind us that the vinedresser in the parable is the Jesus figure who came to save us, not to destroy us, and that Jesus will be our judge, not the Father. he makes it sound as if there's a possible conflict between God the Father, the owner of the vineyard who wants judgment now, and Jesus, the vinedresser who wants to give mercy and grace. He even goes so far as to say that Jesus is lovable, merciful and gracious, but he's not so sure about the Father or the Holy Spirit. So much for unity in the Trinity.

Would you please discuss this parable from a Trinitarian perspective, especially the urgent tone he uses. 

-Warren Wilson