It is worth exploring further the connection between sin and suffering.

Here is an excerpt from Christopher Ash's commentary on Job. It is really worth reading slowly and carefully:

Suffering, which is an anticipation of death, is God’s just penalty for sin: not necessarily individually, but certainly corporately (Romans 5:12). For the unbeliever, every suffering is a foretaste of final judgment and a warning of the horrors of Hell, to which they are heading if they do not repent. When some men asked Jesus about an atrocity, he warned without compromise that unless his hearers repented, these deaths were a foretaste of what they too would have to face (Luke 13:1–5).

But what about the believer? All the sins of the Christian have been borne by the Saviour; he has paid the penalty and has borne the wrath for every one of their sins, conscious and unconscious, past, present, and future. It follows, therefore, that no suffering of believers can possibly be a punishment for their sin. In the light of the cross, it is all undeserved. Of course we deserve it by nature (for by nature we are objects of God’s wrath, Ephesians 2:3). However, before God we are now no longer considered “by nature” but as objects of grace. Logically, therefore, we might expect that Christians ought never to suffer, and this is pretty much what the prosperity gospel teaches. Christ has taken upon himself not only our sin, this view says, but our illnesses and diseases (Matthew 8:17).

And yet Christians do suffer! And Paul makes so bold a statement as to describe his own sufferings as “filling up what is lacking in Christ’s afflictions” (Colossians 1:24). We are called to suffer with Christ if we hope to be glorified with him (Romans 8:17). There is in Christian discipleship a fellowship or sharing in Christ’s sufferings and a becoming like Christ in his death (Philippians 3:10). All this is undeserved, for our sin is paid for and all its entailments covered by the cross. And yet it is necessary. Although they are not payments for anybody’s sin (again- I hope you have got this by now- that was entirely covered by Christ), our sufferings are necessary and have the character of being redemptive suffering (in the sense that they are a part of God’s redemptive plan to bring the gospel to a needy world). They are “for the sake of the elect” (2 Timothy 2:10). To understand this enables us both to see Job’s sufferings as a foreshadowing of the ultimate sufferings of Christ and also to see them as continuing in the sufferings of Christians.

Ultimately any counsel that does not include the Cross of Christ will be discouraging and hurtful. Job's comforters have good intentions, but the impact of their "wisdom" is deeply painful for Job. Since their message is effectively "be good, repent and be blessed", and ignores the gospel of grace, Job will be driven to despair if he believes it. Any message other than the gospel of the cross will ultimately lead suffering men and women to despair. Only the gospel of the cross can bring true comfort, as it leads us to rely not on ourselves, but on God who raises the dead! (2 Corinthians 1:9)