so the Lord slew him. Onan's crime is often misinterpreted to be masturbation but it is universally agreed among biblical scholars that Onan's death is attributed to his refusal to fulfill his obligation of levirate marriage with Tamar by committing coitus interruptus. However, Onan‘s reluctance to give a child to his sister-in-law may reflect a rejection of this custom already present in society. The regulation of levirate marriage in Deut 25:5–10 shows that the custom had encountered some opposition. The law in Deuteronomy allowing a man to refuse his duty was a concession to the reluctance to comply with the custom. Because of Onan's unwillingness to bear a child for his deceased brother, Yahweh was displeased with Onan and slew him also (Gen 38:10). Family tree Interpretation The implication from the narrative is that Onan's act as described is what gave rise to divine displeasure. Early Jewish views One opinion expressed in the Talmud argues that this was where the death penalty's imposition originated. Talmud also likens emitting semen in vain to shedding blood. However, the regulations concerning ejaculation in the book of Leviticus, whether as a result of sexual intercourse or not, merely prescribe a ritual washing and becoming ritually impure until the following evening. Classical Christian views Early Christian writers have sometimes focused on the spilling seed, and the sexual act being used for non-procreational purposes. This interpretation was held by several early Christian apologists. Jerome, for example, argued: Epiphanius of Salamis wrote against heretics who used coitus interruptus, calling it the sin of Οnan:<ref>United States Congress Senate Committee on Government Operations Subcommittee on Foreign Aid Expenditures. Population Crisis: Hearings, Eighty-ninth Congress, Second Session. U.S. Government Printing Office, 1966, p. 403–404</ref> Clement of Alexandria, while not making explicit reference to Onan, similarly reflects an early Christian view of the abhorrence of spilling seed: Roman Catholic views The papal encyclical Casti connubii (1930) invokes this Biblical text in support of the teaching of the Catholic Church against contracepted sex by quoting St. Augustine, "Intercourse even with one's legitimate wife is unlawful and wicked where the conception of the offspring is prevented. Onan, the son of Juda, did this and the Lord killed him for it." Early Protestant views Making reference to Onan's offense to identify masturbation as sinful, in his Commentary on Genesis, John Calvin wrote that "the voluntary spilling of semen outside of intercourse between a man and