Hamartiology is the study of sin. Sin is any failure to conform to the moral law of God in act, attitude, or nature (Grudem). Sin is not only an act of wrongdoing but a state of alienation from God (EDT*).
Sin is anything that violates the law of God or goes against the character of God. God is our perfect standard and it follows logically that anything that opposes Him is sinful.
It is of extreme importance to understand the hatred that God has for sin. It is not merely a distaste or annoyance of sin. It is an intense, fiery hatred. Scripture is clear through and through that God has nothing to do with sin and that he punishes it with harsh justice.
When dealing with the doctrine of sin it is important for us to direct our attention to the origin of sin. First, we must see that God did not create sin and God is not to blame for sin. Satan was the first being to sin and is thus the originator of sin. Adam and Eve sinned in the garden and thus were the first humans to sin.
Even though God did not create sin and is not to be blamed for it, he did ordain that sin would come into the world. God accomplishes all things according to his will. He is a sovereign God who uses all types of situations and events to bring about his good and perfect will.
Adam and Eve disobeyed God and ate from the Tree of the Knowledge of Good and Evil. Satan deceived them and told them that they would be like God. Grudem says it well, “Eve trusted her own evaluation of what was right and what would be good for her, rather than allowing God’s words to define right and wrong.”
When we talk about our inherited sin from Adam, it can be seen in a couple different ways. When Adam sinned, God immediately thought of all mankind who would descend from Adam as having sinned. Just as God imputes Christ’s righteousness to us in our salvation, He also imputed Adam’s guilt to us after he sinned.
We also inherit a sinful nature because of Adam’s sin. The fact that we have inherited a sinful nature does not mean that human beings are as bad as they could be. This is seen in the fact that we have civil laws and convictions of human conscience. It does mean that in our natures we lack spiritual good before God and that we are unable to do spiritual good before God.
We were not only born with sinful natures and with inherited sin, we have all committed actual sins in our own lives (Romans 3:23; 1 John 1:8-10; 1 Kings 8:46). We are all guilty of sin not only because we inherited it, but also because we did it.
Finally, there is punishment for sin. We encounter different consequences for the sins that we have committed on earth while we are alive on this earth. God’s eternal punishment for sin is far worse. God requires a punishment for sin because his righteousness demands it. He would be unjust if He did not punish sin. Punishment for the sin of unbelievers is eternal separation from God in hell.
*EDT stands for Evangelical Dictionary of Theology