The Mortal Sin of Ipsation

Genesis 38:

Then Judah said to [his son] Onan, “Go in to your brother’s wife [Tamar], and perform the duty of a brother-in-law to her, and raise up offspring for your brother.” But Onan knew that the offspring would not be his; so when he went in to his brother’s wife he spilled the semen on the ground, lest he should give offspring to his brother. And what he did was displeasing in the sight of the Lord, and he slew him also.

The Jewish Talmud (“Teaching”), Niddah (“Uncleanness”) 13a-b prohibits "emitting seed in vain".

Rabbi Yoḥanan says: “Anyone who emits semen for naught is liable to receive the punishment of death at the hand of Heaven, as it is stated with regard to Onan”

Rav Asi says: “It is considered as though he worships idols”

Kitzur Shulchan Aruch (compendium of Halakha or Jewish Law) of Rabbi Salomon ben Joseph Ganzfried -

“It is forbidden to discharge semen in vain. […] Those who masturbate and thus discharge semen in vain, not only do they commit a grave sin, but also one who does this is placed under a ban.”

Leviticus 15:16,17,18, and 32 -

“‘When a man has an emission of semen, he must bathe his whole body with water, and he will be unclean till evening.  Any clothing or leather that has semen on it must be washed with water, and it will be unclean till evening…When a man has sexual relations with a woman and there is an emission of semen, both of them must bathe with water, and they will be unclean till evening…These are the regulations for a man with a discharge, for anyone made unclean by an emission of semen….”

St John Cassian - Conferences "Of fornication there are three sorts: [...] (2) that which takes place without touching a woman, for which we read that Onan the son of the patriarch Judah was smitten by the Lord; and which is termed by Scripture uncleanness"

Pope Pius XII - ("this is not lawful: 'masturbation directly procured to obtain sperm'") Allocutio (Oct 8th, 1953)

Clement of Alexandria (The Instructor of Children 2:10:91:2 [A.D. 191]).

"Because of its divine institution for the propagation of man, the seed is not to be vainly ejaculated, nor is it to be damaged, nor is it to be wasted"

“To have coitus other than to procreate children is to do injury to nature.” (The Instructor of Children 2:10:91:2; 2:10:95:3, 375 AD)

St Thomas Aquinas on Whether the unnatural vice is the greatest sin among the species of lust? “Therefore, since by the unnatural vices man transgresses that which has been determined by nature with regard to the use of venereal actions, it follows that in this matter this sin is gravest of all.”

Epiphanius of Salamis in 375 AD stated that, ”They [certain Egyptian heretics] exercise genital acts, yet prevent the conceiving of children. Not in order to produce offspring, but to satisfy lust, are they eager for corruption”

Saint Theodore of Tarsus "the penance is from seven days for the cleric who poured out his seed without touching himself, up to fifty days for the one who voluntarily masturbates […]. Fifty days may seem a lot, but it's tiny when you know that at the same time, a young man touching a virgin woman gets a full year."

Saint Peter Damian - Book of Gomorrah - solitary masturbation is listed as the lowest grade of sodomy “So that the whole matter might be presented to you in an orderly way, I distinguish four types of this nefarious sin.  Some pollute themselves, others are soiled by fondling each other’s male parts, others fornicate between the thighs or in the rear, and these ascend by grades, such that each one is worse than the previous.  Accordingly, the penance that is imposed on those who fall into sin with others is greater than those who dirty themselves alone by the discharge contagion of semen, and those who contaminate others in the rear are more strictly judged than those who copulate between the thighs.  The skilled machination of the devil thus contrives these grades of corruption, so that they more it ascends them, the more deeply the unhappy soul may be plunged into the depths of hell.”

SACRED CONGREGATION FOR THE DOCTRINE OF THE FAITH
Persona Humana 1975

“The traditional Catholic doctrine that masturbation constitutes a grave moral disorder is often called into doubt or expressly denied today. It is said that psychology and sociology show that it is a normal phenomenon of sexual development, especially among the young. It is stated that there is real and serious fault only in the measure that the subject deliberately indulges in solitary pleasure closed in on self ("ipsation"), because in this case the act would indeed be radically opposed to the loving communion between persons of different sex which some hold is what is principally sought in the use of the sexual faculty.

This opinion is contradictory to the teaching and pastoral practice of the Catholic Church. Whatever the force of certain arguments of a biological and philosophical nature, which have sometimes been used by theologians, in fact both the Magisterium of the Church - in the course of a constant tradition - and the moral sense of the faithful have declared without hesitation that masturbation is an intrinsically and seriously disordered act.[19] The main reason is that, whatever the motive for acting this way, the deliberate use of the sexual faculty outside normal conjugal relations essentially contradicts the finality of the faculty. For it lacks the sexual relationship called for by the moral order, namely the relationship which realizes "the full sense of mutual self-giving and human procreation in the context of true love."[20] All deliberate exercise of sexuality must be reserved to this regular relationship. Even if it cannot be proved that Scripture condemns this sin by name, the tradition of the Church has rightly understood it to be condemned in the New Testament when the latter speaks of "impurity," "unchasteness" and other vices contrary to chastity and continence.”

19. Cf. Leo IX, letter "Ad splendidum nitentis," in the year 1054 DS 687-688 [image on right ->], decree of the Holy Office, March 2nd, 1679: DS 2149; Pius XII, "Allocutio," Oct 8th, 1953 AAS 45 (1953), pp. 677-678; May 19th, 1956 AAS 48 (1956), pp. 472-473.

Catechism of the Catholic Church 2352 By masturbation is to be understood the deliberate stimulation of the genital organs in order to derive sexual pleasure. "Both the Magisterium of the Church, in the course of a constant tradition, and the moral sense of the faithful have been in no doubt and have firmly maintained that masturbation is an intrinsically and gravely disordered action."137 "The deliberate use of the sexual faculty, for whatever reason, outside of marriage is essentially contrary to its purpose." For here sexual pleasure is sought outside of "the sexual relationship which is demanded by the moral order and in which the total meaning of mutual self-giving and human procreation in the context of true love is achieved."138 To form an equitable judgment about the subjects' moral responsibility and to guide pastoral action, one must take into account the affective immaturity, force of acquired habit, conditions of anxiety, or other psychological or social factors that lessen or even extenuate moral culpability.

Saint Isidore of Seville regarded masturbation as effeminate and it dishonored manliness.

Saint Jerome Against Jovinian 1:19 [A.D. 393])

But I wonder why he the heretic Jovinianus set Judah and Tamar before us for an example, unless perchance even harlots give him pleasure; or Onan, who was slain because he grudged his brother his seed. Does he imagine that we approve of any sexual intercourse except for the procreation of children?

Saint Augustine (The Good of Marriage 11–12 [A.D. 401]) - “For necessary sexual intercourse for begetting [children] is alone worthy of marriage. But that which goes beyond this necessity no longer follows reason but lust.”

“The reason why we have such massive slaughter of the innocents […] is because in the super-developed nations, like our own, we have become a fornicating society, an adulterous society, a masturbating society, a homosexual society, and a contraceptive society. Unchaste people are selfish people. They will not stop at murder if an unborn child would be a burden to their indulgence and sexual pleasure.”

Fr. John A. Hardon, S.J.

“Just as our rational mind is opposed to artificial insemination, so the same ethical reasoning, by that norm of behavior which is proposed, altogether prohibits that human semen be procured by means of masturbation, not even so as to be subject to the examination of experts.

This norm of behavior we likewise mentioned in our Address before the Congress of the Association of Urological Physicians, on the 8th day in the month of October in the year 1953, in which we decided these things, saying: ‘concerning the rest, the Holy Office has already decided on the 2nd of August, 1929’ (Acts of the Apostolic See, vol. 21, year 1929, p. 490, II) that ‘masturbation directly procured so as to obtain sperm’ is not licit, no matter what the purpose of the exam may be. (Address and Radio message, vol. 15, page 368).’

This mode of procuring human seed, by the effect of masturbation, cannot be viewed as anything other than direct, for it is not in accord with nature, in its full exercise of the generative faculty in the human person. Indeed, because this full exercise was done outside of conjugal intercourse, it bears within itself the direct and improper usurpation of the use of this same faculty. In this way, the improper use of this faculty is rightly considered an intrinsic violation of the principles of morality. For by no means does the human person have the right to any exercise of the sexual faculty beyond a certain point, because he received the very same faculty from nature.

This being so, masturbation is entirely outside of the aforementioned natural capacity of the full exercise of the sexual faculty, and therefore it is also outside that connection to the end ordained by nature. For that same reason, it is deprived of any designation as a right, and also it is contrary to nature and the moral law, even if it is intended to serve a usefulness which is just and not improper.”

Fertility and sterility, Pope Pius XII, 19 May 1956

See now the other Monotheists in Islam:

With regard to masturbation, the basic ruling is that it is prohibited according to the majority of scholars, and the one who does it should be given a Ta`zir punishment (punishments that are not fixed in Islam and are decided by the ruler), but it is not like Zina. And Allah knows best. (Al-Fatawa Al-Kubra, 3/439) 

Dedicated to Saint Joseph - Ite ad Ioseph!