They show that the work of the law is written on their hearts, while their conscience also bears witness, and their conflicting thoughts accuse or even excuse them.
A number of weeks ago this question came up at Bible study. The conscience also surfaced in a recent sermon. I thought I’d give my best answer to this question, recognizing it is a question and not an absolute of the faith and with the recognition that whether it is correct or not we all have a conscience now!
I answer the question in the affirmative, yes Adam and Eve had a conscience, even before the Fall.
Having a conscience was an integral part of being created in God’s image (Gen 1:27), to have God’s law written on their hearts. Conscience is a broader evaluative instinct than good and evil and includes differentiating between useful/worthless, helpful/unhelpful, true/false, good/bad. Adam and Eve clearly had a factual knowledge of right and wrong before the Fall for Gen 2:16–17 tells us:
And the LORD God commanded the man, saying, “You may surely eat of every tree of the garden, but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat of it you shall surely die.”
That they possessed a factual knowledge of right and wrong is the only thing that makes the serpents trickery logical (for tricking involves making someone believe that what is wrong is actually right). So when the serpent comes along and lies, bearing in mind that at this point our first parents had complete free will (now we only have free will to act according to our nature-sin) their consciences were likely screaming. However, Satan’s trick was to confuse them, or deceive them, such that they were willing to suppress their conscience and choose wrongly.
6 So 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. (Gen 3:6)
You might be thinking at this point, “but they had not yet eaten of the tree of the knowledge of good and evil so how could they know what evil was?” They didn’t, though they know what wrong was. We read on (Gen 3:7-8):
7 Then the eyes of both were opened, and they knew that they were naked. And they sewed fig leaves together and made themselves loincloths.
8 And 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.
They had a conscience before the Fall (a factual knowledge of right and wrong), yet they did not have an experiential knowledge of good and evil until after the Fall. The main difference was that before the Fall they had not known evil and therefore had a clear conscience. After the Fall—for the first time— they had a guilty conscience because they knew they were naked and were afraid to meet God.
What about Gen 3:22 then, lest “they become like us knowing good and evil.” That is best explained as God’s foreknowledge of evil.
The long and the short, I would suggest Adam and Eve had a conscience before the Fall
The Lord’s Sweetest Blessings,