Sin

“Christian Theology” by Millard J Erikson states, “Sin is any lack of conformity, active or passive, to the moral law of God. This may be a matter of act, of thought, or of inner disposition of state.” The first of the Ten Commandments (Ex 20:2-3) can be thought of as an alternate definition of Sin: Sin is simply failure to let God be God. Page 170 of our textbook has a good definition as well.

Sin is not evil. There are many "good" people in this world that are nevertheless sinners. In fact, equating sin to evil, complicates our discussions with non-Christians. Sin is not just a moral concept; it is ultimately a theological concept in our relationship with God.

Rom 5:12-19 and p 202 of the book defines original sin: we are all sinners when we accept or approve of our corrupt nature whether or not we have done anything wrong.

Matt 12:31-32 and Mark 3:28-29 define the "unpardonable sin". The simplest interpretation is that the unpardonable sin is deliberately rejecting the work of the Holy Spirit (& implicitly Jesus & God Himself) for our salvation. If we commit this sin, then of course we cannot be saved.