What IS good, and how do we determine it?

[Catholic_Lady]

If you believe the story about Onan in the OT was written word for word, literally as it happened, then yes, you are correct about the last sentence there. As I said, I believe the OT was written allegorically. I believe the point of this story was to teach that contraception is immoral, and that's an important point. But I do not believe God literally "killed" Onan, or that a man named Onan even existed. I cannot speak for those who think otherwise, though.

Whether there was an Onan or not, the interpretation of Onan by the church has always puzzled me.  It's been used to justify both prohibiting contraception (your interpretation) and also masturbation.  But both readings torture the actual story.

Jewish law required if a man died childless, his living brother must marry and have sex with his sister-in-law until she produced a son, and that the son must be raised as the heir of the dead brother:

5 When brothers reside together, and one of them dies and has no son, the wife of the deceased shall not be married outside the family to a stranger. Her husband’s brother shall go in to her, taking her in marriage, and performing the duty of a husband’s brother to her, 6 and the firstborn whom she bears shall succeed to the name of the deceased brother, so that his name may not be blotted out of Israel. 7 But if the man has no desire to marry his brother’s widow, then his brother’s widow shall go up to the elders at the gate and say, ‘My husband’s brother refuses to perpetuate his brother’s name in Israel; he will not perform the duty of a husband’s brother to me.’ 8 Then the elders of his town shall summon him and speak to him. If he persists, saying, ‘I have no desire to marry her’, 9 then his brother’s wife shall go up to him in the presence of the elders, pull his sandal off his foot, spit in his face, and declare, ‘This is what is done to the man who does not build up his brother’s house.’ 10 Throughout Israel his family shall be known as ‘the house of him whose sandal was pulled off.’

Deuteronomy 25:5-10 NRSVACE

Judah had two sons Er and Onan.  When god killed Er for wickedness, Judah told Onan to perform his duty to Er's wife by marrying her and raising thier first born child as Er's.  

It happened at that time that Judah went down from his brothers and settled near a certain Adullamite whose name was Hirah. 2 There Judah saw the daughter of a certain Canaanite whose name was Shua; he married her and went in to her. 3 She conceived and bore a son; and he named him Er. 4 Again she conceived and bore a son whom she named Onan. 5 Yet again she bore a son, and she named him Shelah. She[a] was in Chezib when she bore him. 6 Judah took a wife for Er his firstborn; her name was Tamar. 7 But Er, Judah’s firstborn, was wicked in the sight of the Lord, and the Lord put him to death. 8 Then Judah said to Onan, ‘Go in to your brother’s wife and perform the duty of a brother-in-law to her; raise up offspring for your brother.’ 9 But since Onan knew that the offspring would not be his, he spilled his semen on the ground whenever he went in to his brother’s wife, so that he would not give offspring to his brother. 10 What he did was displeasing in the sight of the Lord, and he put him to death also.

Genesis 38:1-12 NRSVACE


Onan spilled his seed because he did not want to give his child to his dead brother Er.  God was displeased and killed Onan.  Now, we know for certain that avoiding his duty to give a child to his brother was displeasing to god, because it was a violation of the law.  How do you get from there to declaring the method by which he broke the law to be bad under all circumstances.  If that were the case, you'd expect there to be a law in Deuteronomy prohibiting birth control. 

The Christian interpretations of this story are like reading a tale about how a man used a hunting rifle to kill his brother and was then hung, as a moral story about why we shouldn't shoot rifles.

^Yes, and what you say above it the interpretation the protestants use.

The thing is though, that even if Catholics interpreted the story like the protestants, we'd still have the same beliefs about contraception/masturbation. The story of Onan is not the reason why we believe what we do about those 2 issues. I have already written about the reason for contraception, and Onan was in no part of it. It's just kind of like "oh, and here's an example." But we don't base our moral views on it solely on it.