1. It has sometimes been argued that all sins are equally serious. All violate the same first moral principle, all are unreasonable, and so all seem alike in evil. Moreover, all sins offend God’s infinite goodness and so seem somehow infinite in their own right.
2. Nevertheless, common sense and divine revelation agree that not all sins are equally serious (see S.t., 1–2, q. 73, a. 2). In his trial before Pilate, Jesus remarked that the one who handed him over was guilty of a greater sin than Pilate’s (see Jn 19.11). Similarly, warning against officiousness, Jesus says: “You hypocrite, first take the log out of your own eye, and then you will see clearly to take the speck out of your brother’s eye” (Mt 7.5). Beam and mote are both sins, but the sin of the hypocrite is greater than the fault he or she would correct in another.
St. Basil makes the point that even among serious sins, not all are equally grave. Circumstances can make a sin more or less grave. “Suppose it is fornication that is brought to judgment. But the one who committed this sin was trained from the beginning in wicked practices; for he was brought into life by licentious parents and was reared with bad habits, in drunkenness, reveling, and with obscene stories. If someone else, however, had many invitations to better things,—education, teachers, hearing more divine discussions, salutary readings, advice of parents, stories which shape character to seriousness and self-control, an orderly way of life,—if he falls into the same sin as the other, how were it possible, when he is called to account for his life, that he would not be regarded as deserving of a more severe penalty than the other?” (FEF 957). This analysis also develops a saying of our Lord: “Every one to whom much is given, of him will much be required” (Lk 12.48).
3. The difference in the seriousness of sins can arise from the following sources: what one does (sometimes called the “matter” of the act), one’s awareness of wrongdoing in acting, whether one actually makes a sinful choice, and the appeal of a morally acceptable alternative to the sinful choice. The more serious the matter, the more clear the knowledge which forbids the act, and, assuming consent, the easier a right choice of an appealing alternative, the worse the sin.
4. The following considerations make it clear why not all sins are equally serious. Although moral evil does consist in unreasonableness, unreasonableness is not simply the violation of a unitary principle. One violates the first principle of morality by violating various goods in various degrees and also by violating various modes of responsibility whose violation is more or less radically at odds with a will toward integral human fulfillment. Hence, while all sins are unreasonable, their unreasonableness is subject to degree.
5. Similarly, morally evil action is sinful not by violating divine goodness in itself—for it is inviolable—but by violating what participates in divine goodness. Although all sins offend God, not all are equally offensive to him, since not all encroach to the same degree upon the human good he loves.
It is worth considering how sins differ in seriousness according to differences in the seriousness of what one does, setting aside, for the present, differences arising from degrees of awareness or the appeal of the good alternative.
The modes of responsibility have normative force in various ways (see 10‑A). In three different ways, Titus brings about the death of another person, and in each case other factors are assumed constant. The sin which violates the seventh mode of responsibility is more serious than that which violates the fifth, and the sin which violates the fifth mode is more serious than that which violates the first. The difference is not in the damage done, yet it is in what Titus does; for what he does is not simply bring about three deaths, but wrongly determine himself in three diverse ways with respect to the good of human life.
It is important to bear in mind that the same act can violate several modes of responsibility at once. If so, its seriousness is increased. For example, many violations of the seventh and eighth modes of responsibility also involve a violation of the fifth mode. Most abortion and euthanasia of defective persons violate both sanctity of life and fairness; such acts are more seriously wrong than would be the mercy killing of a person who really wished to be killed; for such a killing would not be unfair although it would violate the sanctity of life.
The seriousness of what is done also differs according to the good violated. In the light of faith and within its perspective, acts which directly violate the religious relationship are more serious than those which of themselves violate only a relationship among human persons or groups, and the latter are more serious than those which of themselves violate only the harmony within oneself.
In comparing the seriousness of what is done according to differences in the good violated, one must bear in mind that the same act often violates several goods at once. For example, a Christian who commits adultery violates the religious good of the sacrament, fairness to the injured spouse or spouses, and the good of authentic sexual communion.
The seriousness of what is done also differs according to the extent to which the relevant good is violated (see S.t., 1–2, q. 73, a. 3). For example, those who seek revenge act in a more seriously wrong way if they intend to kill than if they intend only to injure. Injuries to a person are more serious than comparable injuries to an extrinsic good of the person—for example, it is worse to scratch an enemy’s face than to scratch the finish on his or her car. Such differences generally can be distinguished easily enough by asking which injury one would prefer to avoid to oneself. The extent of violation of a relevant good also can be measured by the number of persons adversely affected. For example, the vindictive killing of a whole family is worse than the killing of a single member of the family.
Considering seriousness from a properly Christian perspective, what one does is more seriously wrong if it is more clearly inconsistent with the teaching of the gospel; likewise, what one does is more seriously wrong if it more greatly impedes the life and activity of the Church.
The preceding distinctions—which are not necessarily exhaustive—do not form a single system. Differences in seriousness can be measured in many incomparable ways. One might imagine that if all of these could be applied simultaneously, one could discern a gradation in seriousness proceeding by very small steps from the most grievous to the least serious matters. However, we are in no position to construct such a hierarchy, nor is there any real need to attempt it.
Someone might suppose that comparisons between sins according to the seriousness of what is done involve proportionalism. This supposition would be false. Proportionalism consists in an effort to commensurate the incommensurable—to determine what possibility morally ought to be chosen by comparing various human goods without the use of a prior moral standard to measure them. The comparisons made in the present section involve no such effort. Moral standards are used in making the comparisons.