Q. 15: What was the sin whereby our first parents fell from the estate wherein they were created?God had made our first parents, Adam and Eve, in knowledge, righteousness, and holiness. He had given them dominion over all the earth and an abundance of plants and trees producing food for them. They could eat of any tree of the garden, except for one, the tree of the knowledge of good and evil, on pain of death (Gen. 2:16-17). It was to be a symbol of God’s authority, a reminder that everything else was given by his generosity, and a test of man’s loyalty to his Creator.
Answer: The sin whereby our first parents fell from the estate wherein they were created, was their eating the forbidden fruit. (WSC)
Yet, despite all these good and generous provisions, our first parents violated God’s law by eating this forbidden fruit. In doing so they rebelled against God, aligned themselves with his enemy (the serpent), and demonstrated ingratitude for God's gifts, unbelief in his word, and the proud desire to be as God. This was the sin that broke the covenant of works and caused their fall from their first estate.
Genesis 3 describes how this sin took place. A serpent came to tempt Eve to sin, a serpent who is identified in Revelation 12:9 and 20:2 as the one who is called “the devil” and “Satan.” In John 8:44, Jesus described the devil as “the father of lies” and “a murderer from the beginning.” While he was good when originally created by God, yet this has been his character since he first came on the scene in Genesis 3. The devil was filled with malice as he came as a serpent to destroy mankind. He achieved this destruction by deceiving Eve, persuading her with lies to doubt God’s word and to desire and eat the forbidden fruit. She then gave Adam the fruit and he ate, knowing that it was forbidden. The devil continues to prowl around, seeking someone to devour (1 Peter 5:8), so be watchful and prayerful that you might not succumb to temptation. And be grateful that this sin was not the end of the story. While it caused immense harm for all mankind, it also set the stage for God’s glorious work of redemption.