In John 9, we read of some amazing works of God, most especially the giving of sight to a man born blind. But before we even get to the miracle, there is an important first question raised by the disciples. Indeed, though John does not tell us how Jesus or his disciples knew that this man was blind from birth, their encounter with him prompts a deep question: “Rabbi, who sinned, this man or his parents, that he was born blind?” (John 9:2 ESV). What they’re getting at here is a deeper question that I imagine is universally pondered. That question can be restated like this: what is the relationship between sin and suffering?
Now, we should note right away that they’re not asking this question without tentative answers of their own. In fact, the whole question is couched in terms of what can be called a mechanical relationship between sin and suffering. A mechanical relationship between sin and suffering works something like a gumball machine. When you put a quarter in the gumball machine and turn the crank, out will come your reward. In a similar way, when you sin, you will suffer. This is the mechanical relationship between sin and suffering, the perspective from which Jesus’ disciples ask him this question.
This is the perspective, more or less, of Job’s friends as they come to “comfort” him. Because he sinned (even if he doesn’t know exactly how), he is suffering. If he will only confess his sin, he will stop suffering. This is also the perspective of many today who would invoke the idea of karma. So often, there is something ingrained in us that wants to see the car that just blew past us on the highway get pulled over a half mile down the road. But, I also think that it is equally true that we only want this mechanical relationship to work for others! Let karma be true for thee, but not for me. I would like grace, please.
Now, returning to the disciples’ question, things are somewhat more complicated on account of the congenital nature of this man’s suffering. Likely, this is precisely why the question arises. We might be comfortable with a mechanical relationship between speeding and getting a ticket, but everything is turned upside down when this man “did nothing” and yet is still suffering.
So, then, when we stick with a mechanical relationship that includes a level of personal agency in sin, we’re left with this question: Can this man really have sinned in utero such that he has suffered with blindness from birth? D.A. Carson notes that some rabbis did suggest that Jacob and Esau suffered in their lives on account of their striving with one another in Rachel’s womb, after all. But that doesn’t appear to be reasonable to Jesus’ disciples, so they present the alternative: is he suffering because of the sins of his father? They could certainly think of one possible example of this in the suffering of David’s first child with Bathsheba. In the end, though the disciples seem to be coming from the position of Job’s friends, they’re challenged by the congenital nature of this man’s suffering, and so they put the question to their master.
Interestingly, Jesus responds, but he doesn’t directly answer the question. In fact, rather than going back to past sins in order to neatly answer this vexing question, he points forward to what he’s going to do about this man’s suffering. While that isn’t a direct answer, we should acknowledge a subtle response to the actual question posed to him. By reframing the matter as an opportunity to bring glory to God, our Lord forces us to think bigger than assigning blame to one person or another. We are, instead, invited to consider the potential for God to glorify himself in the present suffering of this world.
The missing piece in all of this, at least at this point in Jesus’ public ministry, is that Jesus will be dealing with sin and suffering once for all and beginning at the cross. The healing of this blind man blows up any mechanical relationship between sin and suffering because Christ, the sinless one, suffers on the cross so that we, the worst of sinners, might be free. In the end, sin and suffering are decoupled in Christ, and because of that we are invited to give all glory to God through Christ.
 Need reference from commentary