There are a lot of characters in the Bible, and most of them are utterly impossible to remember. It’s like One Piece but worse, because nobody in the Bible is an adult baby or a newspaper albatross or something. It’s an interminable cascade of unremarkable patriarchs, so the list of Bible guys who have actually managed to maintain any kind of Q rating into the modern day is remarkably short.
Let’s set aside characters like Jesus, Moses or Noah, because they’re really main characters—Straw Hats, if you will. I’m more interested in guys who survive as echoes, linguistic phantoms, rhetorical devices rather than characters unto themselves. Literal figures of speech, I guess!
A Judas betrays, a Thomas doubts. A Jezebel is an immoral woman. Solomon is a paragon of wisdom. The Queen of Sheba still stands as a personification of ostentatious wealth. And Onan, second son of Judah, is a guy who got caught whacking oft by God.

The first known use of “Onanism” as a euphemism for jarking it was in 1718, and it continues to be used this way today. In particular, it has connotations of profligacy, and one might be accused of intellectual or financial Onanism. Still, that use case references the popular understanding of Onan as a guy infamous for cranking or wanking his dick or cock.
But here’s the thing: Despite only being known as the guy whose rampant penis-pistoning moved the God of Abraham to personally murder him, there is no textual support for this. In fact, it may surprise and alarm to you know that the sad tale of Onan involves precisely no flaying the emperor. For the whole story, cue up your KJV to Genesis 38:6-10:
And Judah took a wife for Er his firstborn, whose name was Tamar. And Er, Judah’s firstborn, was wicked in the sight of the LORD; and the LORD slew him. And Judah said unto Onan, Go in unto thy brother’s wife, and marry her, and raise up seed to thy brother. And Onan knew that the seed should not be his; and it came to pass, when he went in unto his brother’s wife, that he spilled it on the ground, lest that he should give seed to his brother. And the thing which he did displeased the LORD: wherefore he slew him also.
NOW we’re getting somewhere. The saga actually begins with Onan’s dad, Judah. He procures Tamar as a wife for Oman’s older brother Er, who is then personally killed by God for nonspecific wickedness. Judah, seemingly a Tywin Lannister type, calls on Onan to marry Tamar. Onan does marry her, but pulls out whenever they fuck. THIS is the sin God observes, and the reason He subsequently murders Onan (possibly in the Conservatory with the candlestick).
It’s not actually a story that pivots upon the sinfulness of churning the butter once or twice, it’s a story about enforcing the vagaries of Levirate marriage. It’s not uncommon around the world, and the flavor of Levirate marriage featured in this story is the ancient Jewish custom of yibbum. As the younger brother of Er, Onan was supposed to marry and care for his widow, yes, but also any children of that union would legally and spiritually be considered the children of Er. This is what the KJV is trying to get at with the phrase “lest he should give up his seed to his brother.”

So God was mad that Onan blasted ropes on the ground, but only insofar that this was counter to God’s specific request that Onan blast ropes in Tamar. It’s not a lesson about the sacred nature of semen, and the perils of buffing one’s juff; it’s a lesson about the importance of acquiescence to cultural laws, even when doing so is counter to one’s own preferences.
For what it’s worth, Judaism did and does have an alternative ritual to yibbum called halizah, in which widow and brother-in-law formally agree not to get married. Some scholars believe that this story is actually about a situation in which Onan would have preferred halizah, but Judah pressured him to choose yibbum. Onan is willing to marry and care for Tamar, but is reluctant to spend his whole life as step-dad to his own biological children. Therefore, he tries to pull a fast one on Yahweh by fucking Tamar but coaxing out his jism on her lumbar region.
The sin isn’t shooting his shark, it’s trying to exploit a loophole in God’s laws. It’s trying to find some kind of agency in a situation where his sexuality is being restricted to dutiful procreation. It’s having his cake and frosting it too. And for that, God cut the brakes on his camel or whatever.
So the next time you draw the blinds, light the candles and prepare to polish your pecker just so, take just a moment to consider the proud legacy of Onan: The Bible guy killed by God for fucking his sister-in-law incorrectly, and subsequently maligned as a compulsive cockchafer for three thousand years.
There but for the grace of God go you or I.