One of the most moving and powerful miracle stories in John’s Gospel is introduced almost casually: “As Jesus went along, he saw a man born blind” (John 9:1).

The man’s healing was to perplex and infuriate the super-spiritual people, the Pharisees who thought Jesus wasn’t good enough to heal, but lead to one of the greatest declarations in all spiritual experience: “One thing I know, I was blind, but now I see” (verse 25).

Behind the miracle, though, there’s an assumption: that the man’s affliction must be someone’s fault.

Any kind of affliction is hard to bear. It’s even harder when people say it’s your own fault. Jesus’ disciples assumed that someone must have done something wrong, either the man or his parents (verse 2). Somehow he must have deserved it.

That’s a view that is very tenacious. It was expressed by US evangelist Pat Robertson, who said that the people of Haiti were paying the penalty for the sins of their ancestors when the earthquake struck in January 2010. It was said of people with Aids. At an everyday level it can lead to stigmatizing people with disabilities, so that they’re seen somehow as less than adequate.

It’s easy to write off these beliefs as due to ignorance or prejudice. But ideas like this reflect a deep-seated human instinct for justice. The idea that tragedy is random is abhorrent to us. Whether we have faith or not, it doesn’t fit with the way we believe the world ought to be.

There are different ways of dealing with this. Atheists like Richard Dawkins simply deny there is anything to explain. The world is as it is, and there’s no point in complaining about it. Others look for someone to blame. But what Jesus tells his disciples challenges all those ways of thinking.

“It was not that this man sinned, or his parents, but that the works of God might be made manifest in him,” he says (verse 3).

He shifts the emphasis away from explanation to action: given that this has happened, how is it to be made to manifest God’s glory?

This is a radical change. Instead of looking to explain the man’s situation, he is going to change it. He moves the debate from analysis to effect, and does something that glorifies God.

So this is a story that teaches us three things.

1. Explanations aren’t enough

Christians are good at analyzing what’s wrong with the world. We can see poverty, injustice and godlessness and explain exactly what effect they’re having on people’s lives. Karl Marx saw exactly the same thing in his own day, and famously wrote: “Philosophers have only interpreted the world. The point is to change it.” Christians are to be world-changers, not just world-interpreters.

2. We are responsible

In Jesus’ day, they thought people deserved their suffering because God was punishing them. Jesus turned this on its head: suffering is an opportunity for service. Blaming other people for what’s wrong with the world is a way of refusing to take responsibility for changing it.

3. Service is mission

It was the mighty work done in the blind man’s life, the gift of sight, that glorified God. When we do good, through a single intervention or through long-term love, care and commitment, and help change someone’s life for the better, we’re giving them a powerful testimony of the grace of God. Nothing we do is wasted.