We live in an imperfect world in which suffering is a fact of life and we cannot eradicate it. We are vulnerable and susceptible to suffering and death, unscrupulous humans even intentionally inflict suffering upon others. Suffering has many causes: war, poverty, disease, bereavement and depression are only a few, but some types of suffering can be beneficial - pain can alert us to the need for medical assistance, for example, and suffering is an important element of human development - the process we usually call growing up.
The Bible provides insight into the origin of suffering, stating plainly that it is the consequence of man’s fallen, sinful state. Ever since sin appeared through the disobedience of Adam and Eve, mankind has been on a downward spiral both of habitual sinful behaviour and of lack of clear direction, worthwhile hope, or knowledge of God...
Therefore, just as through one man sin entered the world, and death through sin, and thus death spread to all men, because all sinned [Romans 5:12 NKJV]
But it also offers hope...
For as by one man’s disobedience many were made sinners, so also by one Man’s obedience many will be made righteous. [Romans 5:19 NKJV].
God is often ridiculed, and accused of allowing suffering to continue without intervening; people ask why God allows suffering. But sadly, mankind has willingly turned his back on God and misses out on God’s blessings towards those who trust him.
“. . . casting all your care upon him, for he cares for you” (1 Peter 5:7 NKJV).
And so the question really could be: what has mankind done for God to intervene and prevent suffering once and for all? The answer is: nothing. However, God’s promise is that Jesus will establish a world that will be free from sin, suffering and death when he returns to the earth and sets up God’s kingdom; that is why the Lord's Prayer says...
“Your kingdom come. Your will be done on earth as it is in heaven” (Matthew 6:10 NKJV).