Objection 1. It would seem that spiritual goods ought to be foregone on account of scandal. For Augustine (Contra Ep. Parmen. iii, 2) teaches that "punishment for sin should cease, when the peril of schism is feared." But punishment of sins is a spiritual good, since it is an act of justice. Therefore a spiritual good is to be foregone on account of scandal.
Objection 2. Further, the Sacred Doctrine is a most spiritual thing. Yet one ought to desist therefrom on account of scandal, according to Matthew 7:6: "Give not that which is holy to dogs, neither cast ye your pearls before swine lest... turning upon you, they tear you." Therefore a spiritual good should be foregone on account of scandal.
Objection 3. Further, since fraternal correction is an act of charity, it is a spiritual good. Yet sometimes it is omitted out of charity, in order to avoid giving scandal to others, as Augustine observes (De Civ. Dei i, 9). Therefore a spiritual good should be foregone on account of scandal.
Objection 4. Further, Jerome [Hugh de S. Cher, In Matth. xviii; in Luc. xvii, 2 says that in order to avoid scandal we should forego whatever it is possible to omit without prejudice to the threefold truth, i.e. "the truth of life, of justice and of doctrine." Now the observance of the counsels, and the bestowal of alms may often be omitted without prejudice to the aforesaid threefold truth, else whoever omitted them would always be guilty of sin, and yet such things are the greatest of spiritual works. Therefore spiritual works should be omitted on account of scandal.
Objection 5. Further, the avoidance of any sin is a spiritual good, since any sin brings spiritual harm to the sinner. Now it seems that one ought sometimes to commit a venial sin in order to avoid scandalizing one's neighbor, for instance, when by sinning venially, one would prevent someone else from committing a mortal sin: because one is bound to hinder the damnation of one's neighbor as much as one can without prejudice to one's own salvation, which is not precluded by a venial sin. Therefore one ought to forego a spiritual good in order to avoid scandal.
On the contrary, Gregory says (Hom. Super Ezech. vii): "If people are scandalized at the truth, it is better to allow the birth of scandal, than to abandon the truth." Now spiritual goods belong, above all others, to the truth. Therefore spiritual goods are not to be foregone on account of scandal.
I answer that, Whereas scandal is twofold, active and passive, the present question does not apply to active scandal, for since active scandal is "something said or done less rightly," nothing ought to be done that implies active scandal. The question does, however, apply to passive scandal, and accordingly we have to see what ought to be foregone in order to avoid scandal. Now a distinction must be made in spiritual goods. For some of them are necessary for salvation, and cannot be foregone without mortal sin: and it is evident that no man ought to commit a mortal sin, in order to prevent another from sinning, because according to the order of charity, a man ought to love his own spiritual welfare more than another's. Therefore one ought not to forego that which is necessary for salvation, in order to avoid giving scandal.
Again a distinction seems necessary among spiritual things which are not necessary for salvation: because the scandal which arises from such things sometimes proceeds from malice, for instance when a man wishes to hinder those spiritual goods by stirring up scandal. This is the "scandal of the Pharisees," who were scandalized at Our Lord's teaching: and Our Lord teaches (Matthew 15:14) that we ought to treat such like scandal with contempt. Sometimes scandal proceeds from weakness or ignorance, and such is the "scandal of little ones." On order to avoid this kind of scandal, spiritual goods ought to be either concealed, or sometimes even deferred (if this can be done without incurring immediate danger), until the matter being explained the scandal cease. If, however, the scandal continue after the matter has been explained, it would seem to be due to malice, and then it would no longer be right to forego that spiritual good in order to avoid such like scandal.
Reply to Objection 1. In the infliction of punishment it is not the punishment itself that is the end in view, but its medicinal properties in checking sin; wherefore punishment partakes of the nature of justice, in so far as it checks sin. But if it is evident that the infliction of punishment will result in more numerous and more grievous sins being committed, the infliction of punishment will no longer be a part of justice. It is in this sense that Augustine is speaking, when, to wit, the excommunication of a few threatens to bring about the danger of a schism, for in that case it would be contrary to the truth of justice to pronounce excommunication.
Reply to Objection 2. With regard to a man's doctrine two points must be considered, namely, the truth which is taught, and the act of teaching. The first of these is necessary for salvation, to wit, that he whose duty it is to teach should no' teach what is contrary to the truth, and that he should teach the truth according to the requirements of times and persons: wherefore on no account ought he to suppress the truth and teach error in order to avoid any scandal that might ensue. But the act itself of teaching is one of the spiritual almsdeeds, as stated above (Question 32, Article 2), and so the same is to be said of it as of the other works of mercy, of which we shall speak further on (ad 4).
Reply to Objection 3. As stated above (Question 33, Article 1), fraternal correction aims at the correction of a brother, wherefore it is to be reckoned among spiritual goods in so far as this end can be obtained, which is not the case if the brother be scandalized through being corrected. And so, if the correction be omitted in order to avoid scandal, no spiritual good is foregone.
Reply to Objection 4. The truth of life, of doctrine, and of justice comprises not only whatever is necessary for salvation, but also whatever is a means of obtaining salvation more perfectly, according to 1 Corinthians 12:31: "Be zealous for the better gifts." Wherefore neither the counsels nor even the works of mercy are to be altogether omitted in order to avoid scandal; but sometimes they should be concealed or deferred, on account of the scandal of the little ones, as stated above. Sometimes, however, the observance of the counsels and the fulfilment of the works of mercy are necessary for salvation. This may be seen in the case of those who have vowed to keep the counsels, and of those whose duty it is to relieve the wants of others, either in temporal matters (as by feeding the hungry), or in spiritual matters (as by instructing the ignorant), whether such duties arise from their being enjoined as in the case of prelates, or from the need on the part of the person in want; and then the same applies to these things as to others that are necessary for salvation.
Reply to Objection 5. Some have said that one ought to commit a venial sin in order to avoid scandal. But this implies a contradiction, since if it ought to be done, it is no longer evil or sinful, for a sin cannot be a matter of choice. It may happen however that, on account of some circumstance, something is not a venial sin, though it would be were it not for that circumstance: thus an idle word is a venial sin, when it is uttered uselessly; yet if it be uttered for a reasonable cause, it is neither idle nor sinful. And though venial sin does not deprive a man of grace which is his means of salvation, yet, in so far as it disposes him to mortal sin, it tends to the loss of salvation.
Source: Summa Theologica (New Advent)