Many Christians, perhaps most, say that the earth was a perfect paradise before Adam sinned ... that there was no death. But, by eating forbidden fruit, Adam ruined God's marvelous creation and has caused everything to die.
To unbelievers, this is a preposterous belief, and they wonder how any intelligent person in the modern world can buy it. If that's what the Bible teaches, they say, it's obviously not a book of truth.
No death on earth until time of Adam about 6,000 years ago? Then what about miles-deep coal and oil (dead vegetation) ... limestone (layers of dead coral and sea creatures) ... and abundance of dinosaur bones?
Christian tradition got the idea that Adam's sin brought death into the world from only a few vague verses, the subject of this Bible study.
Death is not God's design flaw, and the Bible does not teach that anything on earth has ever been immortal.
How would YOU explain this to a scoffing unbeliever?