Sin of Onan: Genesis 38

I fully submit to the Church’s teachings on contraception, so this post isn’t meant to debate the morality of that. I’m honestly wondering a few things from this passage, and would really appreciate some insight from the Bible scholars out there.

It seems that the Church always references the sin of Onan in her stance against contraception. I’ve heard different adaptations of this, one in which God slew Onan because he was instructed to have intercourse with his brother’s wife to preserve his brother’s lineage, not neccessarily because of the contraceptive act. Reading the passage it certainly seems that way, because later Judah “patronized” Tamar after she tricked him into thinking she was a prostitute, and all was well. This passage confuses me for a number of reasons because why would God want Onan to have sex with his brother’s wife in the first place? God is the same yesterday, today, and forevermore, but later in the book of Leviticus, God says in 18:16 “You shall not have intercourse with your brother’s wife; that would be a disgrace to your brother.” He also says in Leviticus 18:15, “You shall not have intercourse with your daughter in law.” How do we know that God didn’t strike him down for sleeping with his brother’s wife? The Bible noted that God also struck down Er, the older brother, for offending The Lord, although it didn’t note the offense. How come He didn’t strike down Judah for his treatment of Tamar as a prostitute? That’s an offense against The Lord too, right?

I mean no disrespect to our Faith, so please be respectful in your replies. I’m not questioning anything the Church teaches. I’m hoping to be enlightened.


Well yes God never changes, we need to be able to read correctly what HE is trying to teach us here.

In the 18:16 passage you need to realize that “Your brother” is still alive.
If you went and slept with her that is adultery.

The case that applies to Onan is a different one.

It has been discussed in the forum and I will link one thread where I posted some comments on why what Onan did was so heinous. (Post # 13)


Well, you see… reads post #13
…yeah… that 'bout covers it.

So, I have 3 questions if I may:

  1. Why did Onan pursue coitus interruptus? I assume under the relevant law, he incurs no responsibility/liability for the offspring - so there appears to be no motivation there.

  2. What is this story intended to teach us? Is it about the ills of contraception - does the complex scenario of the story (by focussing on the benefits of an offspring for the widow) give support to the merits of having children?

  3. At what point in time (history) did following this old law (brother in-law required to inseminate widow…) cease to be the “right thing” to do?

Ah! but there are good reasons for Onan to act the way he did.
You see Onan’s father would divide the inheritance with his children.
If one of them dies with no descendance, the remaining brothers would receive the part due to the dead one. However if the deceased HAD children then they would receive the part belonging to their fathers. Even if they were born of the brother seed they counted as direct descendants of the deceased.
The widow had no rights to inheritance. However children would ensure she would have a more sheltered old age.

  1. Hmmm All of them? The Bible is so full of deep meaning it is proof I think that God inspired it.

  2. Well the Church Jesus founded started early on, right there when the Apostles were alive to taking care of widows and the orphans.
    Once the reason for the law to exist go away the point of law is moot. Therefore not applicable any longer.
    Don’t we have social security nowdays that “should” ensure this?

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