Each time Job's hits their 'words of comfort' 'back over the net' saying they are wrong - his own experience and the experience of many others proves that the innocent do suffer and the wicked often do prosper. For the reader knows from Job 1-2 that his suffering is not because of his sin or wickedness, for Job was 'blameless and upright, he feared God and shunned evil.' (1:1)
While it is generally true that those who are righteous and fear the Lord enjoy peace and blessing (Prob 11:19), Job shows us that the worldview that suffering is a direct result of one's sin is far too simplistic. The reality is, in this fallen world, tainted by sin, the innocent do suffer.
The gospel (the good news of Jesus) shows us that innocent suffering not only exists but God often uses it for his good plans and purposes. For in Jesus, we see the ultimate act of innocent suffering. He was pure and without sin, and yet he suffered the humiliation and injustice of not just suffering ... but dying - being executed by those he made.
Job teaches us that following Jesus doesn't guarantee health, wealth and prosperity (although some preachers teach this). Suffering still comes to those who fear and follow the Lord - either because of the effects of sin in this world, or even as in Job and Jesus' case, to bring about the plans and purposes of God.
The atheist has no answers or hope in the face of suffering. However, the good news of the gospel is that Jesus innocent suffering gives us hope in our own suffering. For Jesus death was followed by his resurrection - meaning he has paid for sin, and has overcome death, and therefore is able to pave the way for a new creation without sin, suffering and death.
The innocent suffering of Jesus gives us sure and certain hope that the righteous will enjoy the peace and blessing of God - not just for a lifetime, but forever. Therefore, our suffering, we ought to reach out to Jesus, and take comfort in the fact that he experienced suffering himself, he knows our suffering and will one day deliver us from our suffering.