The Catholic Church defines Mortal Sin as having three characteristics:
- Grave (serious) matter
- Full knowledge
- Deliberate intent
The Tree of Premeditated Good and Evil
In Genesis 2:17, God gives a single prohibition to Adam. Of the tree in the center of the garden, with the mysterious name "Tree of Knowledge of Good and Evil" in the King James translation, Adam was not to eat. Would doing so be a mortal sin? Let's go through the definition.
- "In the day that you eat of it you shall surely die." That is certainly a "grave" matter.
- God gives very clear and explicit instructions, and the tree is in a clearly marked location. There is no "accidentally" eating from the wrong tree. It could only be done with "full knowledge".
- The tree is named the Tree of Knowledge. The Hebrew word is da'ar, the same word used in Joshua 20, where God establishes "cities of refuge" for those who kill someone "without knowledge". This means not premeditated, but accidentally, in self defense, or in sudden passion.
In Genesis 3:4, every thing Satan tells Eve is a lie. The last claim is no exception: he tells her that the tree is called the Tree of Knowledge because "you will be like God, knowing good and evil". But as with everything else he says, Satan has twisted the name of the tree. The word translated "know" is a different Hebrew word, yada, which means "to be intimately familiar with", the same word used in "And Adam knew his wife Eve, and she conceived and bore a son."
When Eve ate the fruit, it was not a Mortal sin. Why? Eve was deceived. When Adam ate the fruit, it was with full knowledge and deliberate intent - a mortal sin.
The Death of Humanity
Adam's mortal sin was the death of not just Adam, but all his descendants. For in Adam all died. Adam could have chosen to ask God how to redeem the situation. Instead, he plunged us all into sin and death. But Christ, as the 2nd Adam, does what the 1st Adam refused to do, and redeems the situation - raising us to righteousness and eternal life.