What is sin, exactly?

Many churches and church goers often talk about sin...Jesus forgives me of my sin. I need to confess my sin, Jesus died for my sins. Jesus washed my sins away. The sins of the father are visited on the children to the third and fourth generation (Exodus 34:7).


So just what is this sin that Jesus had to die in order to make me whole? Let's start with some very specific verses that give us some insight...


Original Sin: Genesis Chapter 3 recounts the Biblical historical account of Adam and Eve in the Garden of Eden succumbing to the temptations of Satan and the "Forbidden Fruit". Our "human" nature became a "sin" nature, inherited from Adam and passed down to all of mankind from that one act of disobedience to a single, simple command of God.


Inherited sin: Romans 5:12 - The sin "nature" inherited from Adam
Therefore, just as tsin came into the world through one man, and udeath through sin, and vso death spread to all men5 because wall sinned—


Imputed sin: Romans 5:13-14 - The Mosaic "Law" imputes sin (the laws of God make us aware of sin
13 for sin indeed was in the world before the law was given, but xsin is not counted where there is no law. 14 Yet death reigned from Adam to Moses, even over those whose sinning was not ylike the transgression of Adam, zwho was a type of athe one who was to come.


Personal sin: Romans 3:23
 for all have sinned and fall short of the glory of God


Wages of sin: Romans 6:23a
For the wages of sin is death.


So, what is sin, really?
In a nutshell, it is a direct defiance of a command given by God. The 10 commandments are a fairly well know list of "don'ts expressed by God, HOWEVER, it is not the definitive list.


The Mosaic Law was given specifically to the nation of Israel (Exodus 19; Leviticus 26:46; Romans 9:4). It was made up of three parts: the Ten Commandments, the ordinances, and the worship system, which included the priesthood, the tabernacle, the offerings, and the festivals (Exodus 20—40; Leviticus 1—7; 23).
The Laws of God are accounted in the five books of Moses known as the Pentateuch, or Torah which are: Genesis, Exodus, Leviticus, Numbers, and Deuteronomy.


It is through the Law of God that we are condemned as sinners...



James 2:10
For whosoever shall keep the whole law, and yet offend in one point, he is guilty of all.



Romans 3:19, 20
[19] Now we know that whatever the law says, it says to those who are under the law, so that every mouth may be silenced and the whole world held accountable to God. [20] Therefore no one will be declared righteous in God’s sight by the works of the law; rather, through the law we become conscious of our sin.



Galatians 2:16b
... and not by the works of the law: for by the works of the law shall no flesh be justified.




Biblical references to specific categories of sins:
Proverbs 6:16-19

¹⁶ There are six things the Lord hates,
    seven that are detestable to him:
¹⁷         haughty eyes,
        a lying tongue,
        hands that shed innocent blood,
¹⁸         a heart that devises wicked schemes,
        feet that are quick to rush into evil,
¹⁹         a false witness who pours out lies
        and a person who stirs up conflict in the community.

Galatians 5:19-21a

¹⁹ The acts of the flesh are obvious: sexual immorality, impurity and debauchery; ²⁰ idolatry and witchcraft; hatred, discord, jealousy, fits of rage, selfish ambition, dissensions, factions ²¹ and envy; drunkenness, orgies, and the like.


The Bottom Line:
Sin is rebellion against the Will of God. 
Better said, it is willful disobedience to God's expressed ideal's for human behavior.
Sin is doing what is Wrong in God's eyes versus doing what is Right.
How do we know, as humans, what is Right? The Bible, God's written Word, is the sole source or "standard" by which we can gage what is Right, moral, true, and good, and, by contrast, what is Wrong, immoral, false, and bad.

Just to re-iterate, morality is not a subjective thing, based on human reason or rational arguments. (Isaiah 55:8-9)

Morality (right and wrong) is solely the domain of the one true God of the Bible, the God of Creation, the God of Adam & Eve, the God of Noah, the God of Abraham, Isaac, and Jacob, the God of Moses, the God of the Hebrews and the Christians who are followers of our Lord Jesus Christ who is God in the Flesh.