Most go something like this:

Example 1:

If God had constructed the Garden of Eden so that there were no rules and no way for Adam and Eve to do wrong, then Adam and Eve would be effectively forced to obey God. In order for us to be free – which in this case refers to the freedom to follow or ignore God – we have to be able to make choices. Adam and Eve couldn’t have chosen to follow God if they literally had no other choice.

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Or more detailed…

Example 2:

God put the tree of knowledge of good and evil in the Garden of Eden to give Adam and Eve a choice – to obey Him or disobey Him. Adam and Eve were free to do anything they wanted, except eat from the tree of knowledge of good and evil. Genesis 2:16-17, “And the LORD God commanded the man, ‘You are free to eat from any tree in the garden; 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.’” If God had not given Adam and Eve the choice, they would have essentially been robots, simply doing what they were programmed to do. God created Adam and Eve to be “free” beings, able to make decisions, able to choose between good and evil. In order for Adam and Eve to truly be “free” – they had to have a choice.

There was nothing essentially evil about the tree or the fruit of the tree. It is unlikely that eating the fruit truly gave Adam and Eve any further knowledge. It was the act of disobedience that opened Adam and Eve’s eyes to evil. Their sin of disobeying God brought sin and evil into the world and into their lives. Eating the fruit, as an act of disobedience against God, was what gave Adam and Eve knowledge of evil. Genesis 3:6-7, “When the woman saw that the fruit of the tree was good for food and pleasing to the eye, and also desirable for gaining wisdom, she took some and ate it. She also gave some to her husband, who was with her, and he ate it. Then the eyes of both of them were opened, and they realized they were naked; so they sewed fig leaves together and made coverings for themselves.”

God did not want Adam and Eve to sin. God knew ahead of time what the results of sin would be. God knew that Adam and Eve would sin, and would thereby bring evil, suffering, and death into the world. Why, then, did God put the tree in the Garden of Eden and allow Satan to tempt Adam and Eve? God put the tree of knowledge of good and evil in the Garden of Eden to give Adam and Eve a choice. God allowed Satan to tempt Adam and Eve to force them to make the choice. Adam and Eve chose, of their own free wills, to disobey God and eat the forbidden fruit. The result – evil, sin, suffering, sickness, and death have plagued the world ever since. Adam and Eve’s decision results in each and every person being born with a sin nature, a tendency to sin…..