What is covered in chapter five of How Long, O Lord? by D.A. Carson?

D. A. Carson's How Long, O Lord? is a text which examines Biblical passages as they pertain to the suffering of mankind; it is written through the lens of Evangelical Christianity.

Chapter five, entitled "The Suffering People of God," deals with the particular sufferings of Christians who are confronted with growing "anti-Christian pressures" in the West and official persecution in other parts of the world. Carson says the most dominant type of suffering which Christians find "peculiar" is the suffering which is dealt out by God himself—a "fatherly" kind of punishment which is the hallmark of being a child of God and is done for our good so "we may share in his holiness" and steer clear of sin. 

One of the most interesting arguments made here is that many of God's punishments—including war, illness, financial troubles, death, and personal losses—are inherently considered evil and can easily be conflated as the work of Satan. Carson argues we must come to terms with these "ambiguities" so we do not find ourselves caught in a dualistic universe in which neither good nor evil can dominate our lives. In other words, experiencing suffering is not a good thing, but good things can arise out of it. Moving through suffering—and the difficulties of faith and steadfastness that it causes—allows us to become closer to God and more disciplined in our worship. Carson cites Romans 5: 3-4, in which Paul proclaims,

We also glory in our sufferings, because we know that suffering produces perseverance; perseverance, character; and character, hope.

Thus, we gain access to maturity through our suffering, and we come to realize "there is no future in frustration."

Carson expands this discussion to talk about the persecution of godly individuals who are faced with the presence of evil; this sort of suffering transcends the minor annoyances of our everyday lives and involves "taking up the cross" to stand boldly and proudly as a Christian. As Christians, we must make decisions that cost us something in honor of Christ—again, as means of demonstrating faith and building a moral center around which our lives can be led. This is what Carson refers to as "the death of self-interest." To suffer because one is a Christian is to be deemed worthy of one's Christianity; leaders will be particularly faced with this challenge as they are forged in the fires of suffering—a reminder that there are "no shortcuts." 

The chapter closes with some "Questions for Further Study," most of which you must answer yourself: "Give practical examples from your own life of such discipline," "What opposition have you experienced because you are a Christian? Has it done you any harm—or any good?," "Do you want to be a Christian leader?" I hope this provides clarification on the chapter for you!