From The Bible and Birth Control by Charles Provan (a Prot., BTW).
Calvin, John (1509 - 1564); Calvinist
Commentary on Gen. 38:80-10 –
Besides, he [Onan; C.P.] not only defrauded his brother of the right due him, but also preferred his semen to putrify on the ground, rather than to beget a son in his brother’s name.
v. 10: The Jews quite immodestly gabble concerning this thing. …The voluntary spilling of semen outside of intercourse between man and woman is a monstrous thing. Deliberately to withdraw from coitus in order that semen may fall on the ground is doubly monstrous. …This impiety is especially condemned, now by the Spirit through Moses’ mouth… If any woman ejects a foetus from her womb by drugs, it is reckoned a crime incapable of expiation and deservedly Onan incurred upon himself the same kind of punishment, infecting the earth by his semen, in order that Tamar might not conceive a future human being as an inhabitant of the earth.
Henry, Matthew (1662 - 1714); Nonconformist
Commentary on Gen. 38: 1 - 11 –
Onan, though he consented to marry the widow, yet to the great abuse of his own body, of the wife that he had married, and of the memory of his brother that was gone, he refused to raise up seed unto his brother, as he was in duty bound. … Note, Those sins that dishonour the body and defile it are very displeasing to God and evidences of vile affections.
Luther, Martin (1483 - 1546); Lutheran
Commentary on Gen 38: 8 - 10 –
… the exceedingly foul deed of Onan, the basest of wretches, follows. …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. 10. AND WHAT HE DID WAS DISPLEASIN IN THE SIGHT OF THE LORD, AND HE SLEW HIM ALSO.
Onan must have been a malicious and incorrigible scoundrel. This is a most disgraceful sin. It is far more atrocious than incest and adultery. We call it unchastity, yes, a Sodomitic sin. For Onan goes in to her; that is, he lies with her and copulates, and when it comes to the point of insemination, spills the semen, lest the woman conceive. **Surely at such a time the order of nature established by God in procreation should be followed. ** … He was inflamed with the basest spite and hatred. … Consequently, he deserved to be killed by God. He committed and evil deed. Therefore God punished him. … That worthless fellow refused to exercise [love; C.P.]. He preferred polluting himself with a most disgraceful sin to raising up offspring for his brother.
Therefore Onan, unwilling to perform this obligation, spilled his seed. That was a sin far greater than adultery or incest, and it provoked God to such fierce wrath that He destroyed him immediately.
John Wesley (1703 - 1791); Methodist
Commentary on Gen. 38:7 –
The next brother Onan was, according to the ancient usag, married to the widow, to preserve the name of his deceased brother Er that died childless. This custom of marrying the brother’s widow was afterward made one of the laws of Moses, Deut. 25:5. Onan, though he consented to marry the widow, yet to the great abuse of his own body, of the wife he had married and the memory of his brother that was gone, he refused to raise up seed unto his brother. Those sins that dishonour the body are very displeasing to God, and the evidence of vile affections. Observe, the thing which he did displeased the Lord – And it is to be feared, thousands, especially of single persons, by this very thing, still displease the Lord, and destroy their own souls.