Question: "Why do so many people have to experience terrible suffering before death?"
Answer: Suffering is a universal part of our humanity that exists in a fallen world. The question of why there is suffering in death for some and not as much for others is really not answerable. For we reckon things from our human experience and do not understand the infinite mind and purpose of God. In the great faith chapter, we often read of the heroes of the faith but neglect the litany of those unnamed who suffered for their faith (Hebrews 11:33-40). These all died suffering deaths yet are heroes of the faith. They are unnamed and unsung among men, but God values their suffering and includes them in this great chapter of faith as a lesson to us.
Suffering and death are part of the curse of sin on the world (Genesis 3:16-19). Adam and Eve fell, and when they did, they brought to themselves and to all of their descendants the suffering of death. "But you must not eat from the tree of the knowledge of good and evil, for when you eat of it you will surely die" (Genesis 2:17). We know that Adam and Eve did not die physically on the day that they ate of the tree. Adam lived to the age of 930 (Genesis 5:5). But when Adam sinned, he was spiritually separated from God, and this is the first death.
The question of why some suffer at death and others do not could be summed up in one statement: "God is sovereign." That is not just a trite and easy statement. When Jesus healed a man born blind, the disciples questioned Him. "‘Rabbi, who sinned, this man or his parents, that he was born blind?’ ‘Neither this man nor his parents sinned,’ said Jesus, ‘but this happened so that the work of God might be displayed in his life’" (John 9:1-3). In this passage is a principle that can be applied to our question. God allows some to suffer so that "the work of God might be displayed." In other words, God allows some to suffer to bring glory to His name and others not to suffer for the same reason. It is His sovereign will that determines each circumstance. Therefore, we can safely say that no suffering is without a purpose in the plan of God, even though we as finite humans may not see that purpose clearly.
The Apostle Paul suffered much in his life and ministry. A litany of that suffering can be found in 2 Corinthians 11:23-27. Paul was killed for his testimony and according to universal tradition was decapitated after a long imprisonment. However, during this time, he wrote this testimony to Timothy: "I have fought the good fight, I have finished the race, I have kept the faith. Now there is in store for me the crown of righteousness, which the Lord, the righteous Judge, will award to me on that day—and not only to me, but also to all who have longed for his appearing" (2 Timothy 4:7-8). Another purpose for suffering is to be a witness to those watching that God's grace and strength is sufficient to enable a believer to stand in that suffering (2 Corinthians 12:9).
Paul also gives us an example as to how we should view suffering as a child of God. "But he said to me, ‘My grace is sufficient for you, for my power is made perfect in weakness.’ Therefore I will boast all the more gladly about my weaknesses, so that Christ's power may rest on me. That is why, for Christ's sake, I delight in weaknesses, in insults, in hardships, in persecutions, in difficulties. For when I am weak, then I am strong" (2 Corinthians 12:9-10). And Paul also said, "For me to live is Christ, to die is gain" (Philippians 1:21). Therefore, however a believer dies, in suffering or in relative peace, it is but a transition to "face to face" with the LORD. Once that transition has been made, all of the sorrow and pain of the suffering will end. "He will wipe every tear from their eyes. There will be no more death or mourning or crying or pain, for the old order of things has passed away" (Revelation 21:4).