The first mention of sin, as a word or concept, in the Bible is Genesis 4:6 and 7: “Then the LORD said to Cain, “Why are you angry? Why is your face downcast? If you do what is right, will you not be accepted? But if you do not do what is right, sin is crouching at your door; it desires to have you, but you must master it.” After this Cain invited his brother Abel into the field and kills him. Which while it might not be the first sin is the first murder.
However, in Paul’s “Letter to the Romans”, Paul expresses a different view of the first sin. Romans Chapter 5 verse 12 states “Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned.” This is clearly the start of the doctrine of “original sin”. But all this does is raise two questions: who was “the one man” through which sin entered the world? And what was the sin?
In First Corinthians Paul seems to answer the first question in chapter 15 verse 22: “For as in Adam all die, so in Christ all will be made alive.” But he doesn’t go on to answer the second question.
A look at Genesis will seem to give the obvious answer to this second question:
Genesis 3:14-19 states: The Lord God said to the serpent, Because you have done this, cursed are you among all animals and among all wild creatures; upon your belly you shall go, and dust you shall eat all the days of your life. I will put enmity between you and the woman, and between your offspring and hers; he will strike your head, and you will strike his heel.” To the woman he said, I will greatly increase your pangs in childbearing; in pain you shall bring forth children, yet your desire shall be for your husband, and he shall rule over you.” And to the man he said, Because you have listened to the voice of your wife, and have eaten of the tree about which I commanded you, You shall not eat of it, cursed is the ground because of you; in toil you shall eat of it all the days of your life; thorns and thistles it shall bring forth for you; and you shall eat the plants of the field. By the sweat of your face you shall eat bread until you return to the ground, for out of it you were taken; you are dust, and to dust you shall return.”
But looking closely never is the word “sin” used in this quote; the word curse is but not sin. But clearly the Genesis writer is saying that Adam and Eve were in the wrong for disobeying God by eating the forbidden fruit and were being punished, but somehow coyly avoids the actual word “sin.”