“Amen, amen, I say to you: If any man keep my word, he shall not see death forever.”
The Distinction between two types of sin
All sin is an offense against God and a rejection of his perfect love and justice. Yet, Jesus makes a distinction between two types of sins. We call the most serious and grave sins, mortal sins. Mortal sins destroy the grace of God in the heart of the sinner. By their very grave nature, a mortal sin cuts our relationship off from God and turns man away from his creator. St. Paul’s letter to the Hebrews tell us that “if we sin willfully after having the knowledge of the truth, there is now left no sacrifice for sins” (Hebrews 10:26). The second type of sin, venial sin, that of less grave matter, does not cut us off from Christ. However, venial sin does weaken grace in the soul and damages our relationship with God. A person who frequently indulges in venial sin is very likely to collapse into mortal sin if they persist in their evil ways.
So what kind of Sins are Mortal?
In order for a sin to be mortal, it must meet three conditions:
Mortal sin is a sin of grave matter
Mortal sin is committed with full knowledge of the sinner
Mortal sin is committed with deliberate consent of the sinner
This means that mortal sins cannot be done “accidentally.” A person who commits a mortal sin is one who knows that their sin is wrong, but still deliberately commits the sin anyway. This means that mortal sins are “premeditated” by the sinner and thus are truly a rejection of God’s law and love.
The first condition, that a mortal sin is of grave matter, means that certain premeditated offenses against God are more severe than others. We know that some sins are graver than others (e.g. it is a graver sin to murder someone than to lie to someone). St. John tells us, “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. All wrongdoing is sin, but there is sin that is not deadly.” (1 John 5:16-17). Thus St. John distinguishes between mortal and venial sin. Jesus also warns us that “Anyone who does not remain in me will be thrown out like a branch and wither; people will gather them and throw them into a fire and they will be burned” (John 15:6).
What kinds of offenses against God constitute “grave matter”?
In the Bible, St. Paul gives us a list of grave sins. He states that anyone who commits these sins shall not enter the kingdom of God. “Now the works of the flesh are manifest, which are these; Adultery, fornication, uncleanness, lasciviousness, idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies, envyings, murders, drunkenness, revellings, and such like: of the which I tell you before, as I have also told you in time past, that they which do such things shall not inherit the kingdom of God” (Galatians 5:19-20). Paul also tells the Corinthians, “know you no that the unjust shall not possess the kingdom of God? Do not err: neither fornicators, nor idolaters, nor adulterers, Nor the effeminate, nor liers with mankind, nor thieves, nor covetous, nor drunkards nor railers, nor extortioners shall possess the kingdom of God” (1 Corinthians 6:9-10). These sins constitute grave matter, and if they are committed willingly and with full consent, constitute mortal sin.
The Church also tells us that the sins of anger, blasphemy, envy, hatred, malice, murder, neglect of Sunday obligation, sins against faith (incredulity against God or heresy), sins against hope (obstinate despair in the hope for salvation and/or presumption that oneself can live without God or be saved by one’s own power) and sins against love (indifference towards charity, ingratitude, and/or hatred of God) also constitute grave matter. This list of grave sins, is based on Jesus Christ’s interpretation of the gravity of the Ten Commandments. Grave sins can be classed as sins against God, neighbor and self, and can further be divided into carnal and spiritual sins (CCC 1853).
Four other sins are considered grave also. These sins not only offend God, but men as well. Thus these four sins are called “the sins that cry to heaven for vengeance” and are likewise mortal sins. These grave sins are:
The voluntary murder (Genesis 4:10)
Taking advantage of the poor (Exodus 2:23)
Defrauding the workingman of his wages (James 5:4)
Finally, the capital sins are also considered grave matter. These sins are vices and are defined as contrary to the Christian virtues of holiness. They are pride, avarice, envy, wrath, lust, gluttony, and sloth (acedia).
Note from the author: For those of you who do not understand why these particular sins are of grave matter, I would suggest that you refer to the Summa Theologiae of St. Thomas Aquinas. He does an excellent job of explaining why these sins are of grave matter, and also explores the counter-arguments and objections that some people have regarding these grave sins.