In Catholic doctrine, there are two types of sins a person can commit: venial sins and mortal sins. Venial sins are relatively minor, such as being impatient, gossiping, or stealing something of low value. Venial sins are thought to harm an individual’s relationship with God but not irreparably. Mortal sins, however, are those that so egregious that they kill one’s spirit, destroying feelings of charity and grace within him, and thus separating the individual from God. Mortal sins include murder, fraud, and adultery. One may commit a venial sin accidentally, without malice of forethought, but mortal sins are committed deliberately, with a person’s full knowledge.
Dante’s Circles of Hell are modeled on the work of Sir Thomas Aquinas, who, some fifty years prior to Dante’s writing, ranked sins according to their level of offense against God, from least to greatest. Aquinas’s “system” has influenced philosophers, theologians, and writers for hundreds of years.
The worst of the worst sins, according to Aquinas, are known as the “Seven Deadly Sins.” They are:
Additionally, all sin can be categorized as one or more of the following types, from least to greatest offense:
Level One: Incontinence, or lack of self-control
Level Two: Violence, a deliberate violation of God’s will
Level Three: Fraudulence or Traitorousness, using one’s intellect as a weapon