There are no easy answers to the question of the purpose of suffering and evil. The tendency is to blame God for these conditions, but He did not create them. They came as a result of man's disobedience to God, beginning back in the Garden of Eden; see Genesis 3:16-19.
Often suffering and adversity are brought about by disregard of God's will or by the direct efforts of Satan or by natural disasters in a physical world which is also affected by man's sin and the resulting judgment. God, however, has offered the most effective solution possible by giving His Son to die for all.
Jesus Christ paid the ultimate price when He suffered and died on the cross, having taken upon Himself the sin of the world and all of its horrible consequences. When Jesus returns in power and glory, there will be a new world completely free from sin with its sorrow and suffering (Revelation, chapters 21 and 22).
We can be sure that God in His divine purpose desires to bring about in us the greatest good and to allow suffering to be a means of discipline to cultivate love, patience, grace, and faith in our lives. God never asks us to understand; we need only trust Him in the same way that we expect our earthly children to trust our love.
Peace comes when we realize we are able to see only a few threads in the great tapestry of life and of God's plan. Then we can affirm with great joy and assurance that "in all things God works for the good of those who love him, who have been called according to his purpose" (Romans 8:28).
The way we react to suffering will determine whether life's most tragic experiences bring bitterness and despair or become sources of blessing. The greatest joy will come when, in the midst of adversity, we look up into God's face and say, "I will rejoice in the Lord, I will joy in the God of my salvation" (Habakkuk 3:18).
It is then that His promise will be most meaningful, "When you pass through the waters, I will be with you; and when you pass through the rivers, they will not sweep over you. When you walk through the fire, you will not be burned; the flames will not set you ablaze" (Isaiah 43:2).