Adam and Eve were the first humans and they were companions to God. Because God gave us a free will since the beginning, he gave them a choice to eat a fruit he said not to eat. They ate the fruit and knew what sin was. God punished them by kicking them out of the Garden of Eden. He also said there would be pain and pregnancy would be painful. Technically heaven was given to us right away. But because Adam and Eve sinned, we no longer get to heaven right away.
Satan was an ex-angel who tempted Eve, who tempted Adam into eating the fruit. He has power and was able to make the Garden of Eden impossible to reach from earth.
When Jesus came to earth, he defeated Satan by dying on the cross for our sin. Satan has already been defeated, but his goal before he completely goes down is to drag as many people down with him as he can. He tempts people with their weaknesses daily. Thus drugs, love, and alcohol are a big part of our world today. Some temptations aren't all bad. Jesus can "tempt" test us to see if we have really repented of a sin and are willing to go to heaven when we die.
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