Sin is the transgression of God's law. It has a broad application in that sin can be defined as all unrighteousness, missing the mark or falling short of the character of God. Whatever is not of faith is sin, and when a person knows to do good but does not do it, it is sin. The penalty for sin is death in the Lake of Fire. Unpardonable sin is the willful, knowledgeable and continued transgression of the commandments of God. It also includes the willful rejection of God's salvation and blasphemy of the Holy Spirit, which is despising the works God does by the power of His Spirit and attributing them to Satan. These sins are unpardonable because the person will not repent. All sins can be forgiven by God's mercy through the blood of Jesus Christ.
Scripture References:
I John 3:4; 5:17; Ephesians 2:1; Romans 14:23; James 4:17; Romans 6:23; Revelation 20:14; Galatians 5:19-21; Matthew 12:31; Hebrews 10:26-29; I John 1:7, 9; Romans 8:1-3
From the Library: Sin
Admission of Sin
Bible Study by Martin G. CollinsMany believe that the existence of God's law creates the problem of sin, rather than the harm from illicit acts. Upon rejecting God's law, people often claim the freedom to decide right from wrong, refusing to confess or acknowledge their sinful acts due to enmity against God. A world without God's definition of sin may justify …
A Sin Unto Death
'Ready Answer' by StaffSin carries grave consequences for those who stray from God's way of life. When individuals leave God's church due to offense or other reasons, there is little doubt that they have sinned. Any sin can be forgiven if sincerely repented of and confessed to our merciful God, for He is faithful and just to forgive and cleanse from …
Are Some Sins Worse Than Others?
'Ready Answer' by Martin G. CollinsSin carries grave consequences, as the wages of sin is death. Although all sin merits the death penalty and requires the blood of Christ for expiation, some sins are indeed worse than others, bearing greater consequences to the sinner and to those affected by his actions. God's judgments reveal that certain sins bring stiffer …
Sin
Sermonette by James BeaubelleOur carnal nature will always deceive the self, convincing us that our behavior is not so bad, but Paul realized the addictive, toxic nature of sin.
Sin Defined and Overcome
Sermon/Bible Study by John W. RitenbaughSin creates estrangement from God, causing us to fail in everything we attempt. Sin always produces separation; it never heals, but causes death.
Sins in the Balance (Part Two)
CGG Weekly by David C. GrabbeThe Bible is full of commands to forgive and examples of forgiveness, and none of them stipulates that we wait for the sinner to repent before we forgive.
Sin, Christians, and the Fear of God
'Personal' from John W. RitenbaughScripture takes a very stern view of sin because it is failure to live up to God's standard and destroys relationships, especially our relationship with God.

What Sin Is
'Personal' from John W. RitenbaughNo one seems to talk about sin anymore, but it still exists and continues to wreak havoc! Scripture describes sin and what God wants us to do about it.
For more resources, please see the library topic for Sin