Besides God’s goodness and holiness, we must also consider God’s sovereignty and dignity. Sin committed against a sovereign (a ruler) or a person of greater dignity or honor, is worse than the same sin against those of lower station or who are less honorable. But God is the ruler of all and has infinite dignity and majesty. Thus, because every sin is an offense against God, it is an infinite evil because it is against God, Who is the sovereign of all, and Who is infinite in dignity and majesty.
Here is how the Summa explains this truth:
According to the Philosopher [i.e., Aristotle] (Ethic. v, 5), punishment is meted according to the dignity of the person sinned against, so that a person who strikes one in authority receives a greater punishment than one who strikes anyone else. ... But God’s majesty is infinite.
Summa Suppl. Q.99, a.1 sed contra (bracketed word added).
Conclusion: Sin is an infinite (unlimited) evil because it is committed against God, Who is infinitely good and holy, and is the sovereign of all, with infinite majesty.
2. Sin incurs a debt which is infinite, i.e., unpayable by us, without God’s help.
We never merit anything from God by ourselves. We can only merit when we possess God’s grace and only with the help of His grace.
Here is how St. Thomas Aquinas, greatest Doctor of the Catholic Church, teaches this truth:
A man can merit nothing from God except by His ... supernatural gift, which we call grace.
Summa, Ia IIae, Q.114, a.2, respondeo & ad 3.
One of the chief ways to merit is by prayer. But God never hears the prayers of anyone who is not in the state of grace. Here is how Sacred Scripture explains this truth:
“God doth not hear sinners: but if a man be a server of God, and doth His will, him He heareth.” St. John’s Gospel, 9:31.
“If I have looked at iniquity in my heart, the Lord will not hear me.” Psalm, 65:18.
Grace is God’s free gift which He does not owe to us.
Here are St. Thomas’s words, in which he contrasts debts owed in justice, to the gratuitous nature of God’s free and undeserved gift of grace:
There is a twofold giving. One belongs to justice, and occurs when we give a man his due. In this type of giving, [the sin of] respect of persons takes place [viz., fulfilling (or not fulfilling) our duty of justice based on the status of the particular person].
The other giving belongs to liberality, when one gives gratis that which is not a man’s due. Such is the bestowal of the gifts of grace, whereby sinners are chosen by God. In such giving, there is no place for respect of persons, because anyone may, without injustice, give of his own as much as he will, and to whom he will, according to Matt. 20:14 & 15: “Is it not lawful for me to do what I will? ... Take what is thine, and go thy way.”
Summa, IIa IIae, Q.63, a.1, ad 3 (emphasis and bracketed words added; ellipsis in original).
Even the slightest venial sin incurs a debt which (although small compared to the debt incurred because of mortal sin), nonetheless we cannot repay on our own viz., without the help of God’s grace. Mortal sin is much worse, since it involves loss of the grace (if the man had any) which is a help from God which is necessary for a man to merit anything from God and repay any debt to God.
Concerning the offense of even a single venial sin, St. Alphonsus de Liguori, Doctor of the Church, teaches us:
A single venial sin is more displeasing to God than all the good works we can perform.
St. Alphonsus de Liguori, Uniformity with God’s Will, §6.
Thus, by ourselves, we are unable to repay the debt of even one of our sins. That is, repayment for even the smallest sin exceeds the limits of all we can do (thoughts, words and deeds) by ourselves (i.e., without God’s grace).
Conclusion: Sin is an infinite evil because of the debt it creates, which surpasses the limit of any man’s own (unaided) ability to repay, regardless of the length of time and the number of his thoughts, words and deeds.
3. In hell, all sin merits an infinite punishment and mortal sin merits an infinite punishment in two ways.
Sin deserves infinite punishment in hell. Our Lord assures us that the wicked “shall go into everlasting punishment”. St. Matthew’s Gospel, 25:46.
God punishes the damned eternally (i.e.,
without end) not only for their mortal sins but also for their venial sins.
Regarding the eternal punishment of venial sin, here is how the Summa explains this truth:
It is accidental [i.e., incidental] to venial sin that it be punished temporally in purgatory, through its having grace annexed to it [i.e., the venial sin is in a soul which is in the state of grace]: wherefore if it be annexed to a mortal sin, which is without grace, it [i.e., venial sin] will be punished eternally in hell.
Summa Suppl., Q.69, a.7, ad 6 (bracketed words added).
Because God is all-just, it must be true that those venial sins (as well as those mortal sins) deserve punishment which is infinite in duration (i.e.,
without end). Thus, in itself, all sin (including all venial sin), deserves punishment of infinite duration in hell.
Further, in addition to the infinite duration of the punishment which all sin deserves in hell, the punishment for mortal sin is infinite in a second way because through mortal sin the damned deserve to be punished by the loss of the infinite good, which is God.
St. Thomas Aquinas explains that, in hell, “the pain of loss ... is infinite, because it is the loss of the infinite good, i.e. God.” Summa, Ia IIae, Q.87, a.4, respondeo.
Thus, sin deserves infinite punishment according to both of the ways that punishment is measured. Here is how the Summa explains the two ways sin is punished:
[P]unishment is measured in two ways, namely according to the degree of its severity, and according to its length of time ....
Summa Suppl. Q.99, a.1, respondeo.
Beside the infinite duration of the punishments of hell and the damned souls’ loss of the infinite good (which is God), all other punishments of hell are finite because creatures are not capable of suffering punishments of infinite intensity. Here is how the Summa explains this truth:
[P]unishment cannot be infinite in intensity, because the creature is incapable of an infinite quality ....
Summa Suppl. Q.99, a.1, respondeo.
Conclusion: Sin is an infinite evil as shown by the infinite punishment it deserves. All sin deserves punishment of infinite duration (for those in hell) and those in mortal sin also deserve the infinite punishment of being deprived of the infinite good, which is God.
4. Mortal sin is also infinitely more grave than venial sin.
As shown above, every sin (including every venial sin) is horrific and is an infinite evil in three ways.
But every mortal sin is infinitely worse than any venial sin. We see this truth from the fact that no number of venial sins (no matter how many) would be equal to even one mortal sin. In other words, a mortal sin is worse without limit, than a venial sin.
We see that no number of venial sins—no matter how many—would cause a person to lose the sanctifying grace in his soul (if he has any). We see that no number of venial sins—no matter how many—would result in the eternal punishment of hell (without the damned person also having committed mortal sin).
Conclusion of this article
As shown above, all sin is against God (directly or indirectly). All sin is infinitely evil in three ways. Mortal sin is infinitely evil in a fourth way.
Let us avoid all sin because the sins we commit are the only true evil for us!