“Through one man sin entered into the world and death through sin, and so death spread to all men.”​—ROMANS 5:12.

God created our original parents, Adam and Eve, with perfect minds and bodies. He also gave them a paradise home on earth​—called the garden of Eden. He told them that they could eat from all the trees in the garden, except for one. However, Adam and Eve chose to eat some of the fruit from that tree, and that was a sin. (Genesis 2:15-17; 3:1-19) After their disobedience, God expelled the couple from the garden and life became hard for them. In time, they had children, and life was hard for them too. They all grew old and died. (Genesis 3:23; 5:5) We get sick, grow old, and die because we come from that original family.

“The whole world is lying in the power of the wicked one.”​—1 JOHN 5:19.

That “wicked one” is called Satan. He is an invisible spirit creature who rebelled against God. (John 8:44; Revelation 12:9) Later, other spirit creatures joined Satan. They are called demons. These evil spirits use their  power to deceive people and turn them away from the Creator. They influence many people to do bad things. (Psalm 106:35-38; 1 Timothy 4:1) Satan and the demons delight in causing pain and suffering.

“Whatever a person is sowing, this he will also reap.”​—GALATIANS 6:7.

In various ways, we all suffer because of inherited sin and Satan’s influence on the world around us. But sometimes people add to their own suffering. How? When they do bad things or make foolish decisions, they often reap bad results. On the other hand, when people do good things, they reap good results. For example, a husband and father who is honest, works hard, and loves his family will reap many good things and make his family happy. But one who gambles, drinks too much, or is lazy may bring himself and his family into poverty. So we are wise to listen to our Creator. He wants us to reap many good things, including “abundant peace.”​—Psalm 119:165.

“In the last days . . . , men will be lovers of themselves, lovers of money, . . . disobedient to parents, . . . without self-control, fierce, without love of goodness.”​—2 TIMOTHY 3:1-5.

Today, many people behave just as those words foretold. Their behavior adds to the evidence that we are in “the last days” of the present world. The Scriptures also foretold that our time would be marked by wars, food shortages, great earthquakes, and diseases. (Matthew 24:3, 7, 8; Luke 21:10, 11) These things cause much suffering and death.