There are famous passages in the gospels where apparently quite ordinary people become disciples of Jesus, and their lives are transformed.
Jesus, walking by the Sea of Galilee, sees four fishermen and calls them. Immediately, they leave their old lives behind, all those they love and all they have laboured for, and follow him. Levi the tax-collector, too, immediately responds to Jesus' call, abandoning his former way of life apparently without a second thought.
These are impressive stories, in which the immediacy of these men's response to Jesus dramatizes the radical nature of their conversion, their readiness to give up everything to follow the divine call. Jesus expects a prompt and total response, and gets it. These are stories which are liable to leave us feeling a little bemused and not a little inadequate.
But in today's gospel Jesus puts this process of becoming a disciple in a different, less romantic light. Far from calling people to be his disciples, he seems almost intent on putting them off. He starts by telling them that they have to hate all those to whom they have belonged, their entire family.
Even if, when Jesus uses the word 'hate', he is just saying in a dramatic way, and in semitic style, that he expects his disciples to be committed to him to the extent of leaving and even being estranged from their families, this is still hardly an attractive proposition for people of any age, and still less today when we are told so often that the family is for most people the essential context of a good Christian life.
But then Jesus goes still further, saying that any would-be disciple has to be prepared also to die in the most horrible way, to be crucified as Jesus himself will be crucified.
Jesus does not present discipleship as easy, nor even attractive. So it is only logical that he should say, in effect: don't rush into becoming one of my disciples, think about it. It would be silly, a waste of time and money, to start a major building project unless you are fairly sure of having enough money to finish it. Constructing a whole life is a much more important and potentially much costlier project than building a tower, so think carefully about whether you have what it takes to live that life, and whether you are really prepared to pay what it may cost.
As if all that were not enough to make us ask ourselves whether we really wanted to be disciples of Jesus, he gives us an even less encouraging image. Christian life is not like a construction, it is like a war, and what's more a war we are likely to lose, because our enemy is twice as strong as we are. Would it not be more sensible, on reflection, to avoid this war, and come to terms with the enemy?
Jesus is not asking for mere enthusiasm here, but for intelligence and realism. But this is not because he wants to avoid enthusiasm and wholehearted commitment, or to turn people off the idea of being his disciple. What he says here only makes sense if we suppose that he is speaking to those who genuinely want to be his disciples, and that he in turn wants disciples, just as he called those four fishermen by the Sea of Galilee.
Only, enthusiasm is not enough. As Christians we are engaged in building a life, and we are engaged in a war with all that threatens that life. If we are to be good disciples, we need to build and fight well, and that means we have to act intelligently, thinking realistically about our situation and acting accordingly, rather than rushing in blindly armed with no more than good intentions.
Good intentions are vital, but we all know how destructive they can be unless allied to sound reason and accurate perception. We have been given Christ as the sure foundation on which to build, and we have the grace of God to help us in our battle. To use these gifts at all we must be enthusiastic for God; to use them well we must be thoughtful enthusiasts.