Definition of sin

[CCC 1871]:

1871 Sin is an utterance, a deed, or a desire contrary to the eternal law (St. Augustine, Faust 22: PL 42, 418). It is an offense against God. It rises up against God in a disobedience contrary to the obedience of Christ.
  • sin is an offense against God
  • sin is disobedience to God
  • sin is "knowing it is wrong and doing it anyway"

Etymology

from OE synn for "moral wrongdoing, injury, mischief, enmity, feud, guilt, crime, offense against God, misdeed"

  • from PIE *snt-ya-, forming *es-ont- for "becoming"
    • in Germanic language groups, took on meaning of "it is true". as in "the sin is real"

Forgiveness of sin

"Because sin is always an offences against God, only he can forgive it"

Origin of sin in man

For from the heart come evil thoughts, murder, adultery, unchastity, theft, false witness, blasphemy. (Mt 15:19)

Classifications of sin

St. Paul on sins or "works of the flesh":

Now the works of the flesh are obvious: immorality, impurity, licentiousness, idolatry, sorcery, hatreds, rivalry, jealousy, outbursts of fury, acts of selfishness, dissensions, factions (Gal 5:19-20)

From CCC 1853:

Sins can be distinguished according to their objects, as can every human act; or according to the virtues they oppose, by excess or defect; or according to the commandments they violate. They can also be classed according to whether they concern God, neighbor, or oneself; they can be divided into spiritual and carnal sins, or again as sins in thought, word, deed, or omission. The root of sin is in the heart of man, in his free will, according to the teaching of the Lord: "For out of the heart come evil thoughts, murder, adultery, fornication, theft, false witness, slander. These are what defile a man." But in the heart also resides charity, the source of the good and pure works, which sin wounds.

which we can organize as

Classification Types
distinguish sins by their objects

by the virtues they oppose

by the Commandments they violate

sins as against God

against neighbor

against oneself

types of spiritual

carnal

location of in thought

in word deeded omissions

Venial sin

vice

Mortal sin

capital sin

  • "capital sin" or "capital vice" (CCC 1866)
  • also called the "Seven Deadly Sins"
    • pride, covetousness, lust, anger, gluttony, envy, and sloth
  • "capital" because these are the "head" of other sins (i.e., lead to them)
  • "deadly" because they lead to death and damnation

mortal sin

  • "mortal" because it separates us from God
  • 1 Jn 5:16:
If anyone sees his brother sinning, if the sin is not deadly, he should pray to God and he will give him life. This is only for those whose sin is not deadly. There is such a thing as deadly sin, about which I do not say that you should pray.
  • mortal sin may only be removed through the Sacrament of Reconciliation

the "Unforgiveable sin"

From Mt 12:30

Therefore, I say to you, every sin and blasphemy will be forgiven people, but blasphemy against the Spirit will not be forgiven.
  • per USCCB Bible footnote Mt 12:31: "Blasphemy against the Spirit: the sin of attributing to Satan (Mt 12:24) what is the work of the Spirit of God (Mt 12:28).

Mt 12:31:

And whoever speaks a word against the Son of Man will be forgiven; but whoever speaks against the holy Spirit will not be forgiven, either in this age or in the age to come.