Westminster Shorter Catechism - Question 13 & 14

Genesis 3:6-8

⁶So when the woman saw that the tree was good for food, and that it was a delight to the eyes, and that the tree was to be desired to make one wise, she took of its fruit and ate, and she also gave some to her husband who was with her, and he ate. ⁷Then the eyes of both were opened, and they knew that they were naked. And they sewed fig leaves together and made themselves loincloths.

⁸And they heard the sound of the Lord God walking in the garden in the cool of the day, and the man and his wife hid themselves from the presence of the Lord God among the trees of the garden.

Ecclesiastes 7:29

²⁹See, this alone I found, that God made man upright, but they have sought out many schemes.

2 Corinthians 11:3

³But I am afraid that as the serpent deceived Eve by his cunning, your thoughts will be led astray from a sincere and pure devotion to Christ.

Did our first parents continue in the estate wherein they were created?

Our first parents, being left to the freedom of their own will, fell from the estate wherein they were created, by sinning against God.

What is sin?

Sin is any want of conformity unto, or transgression of, the law of God.