After the death of his brother Er, Onan was instructed to fulfill his family responsibility by providing offspring for his brother's widow, Tamar. Instead, he deliberately prevented conception, knowing that any child born from the union would be regarded as his brother's heir. Genesis tells us that his conduct was wicked in God's sight and that God put him to death. What made his offense so serious?
Puzzling Passages
Why Did God Put Onan to Death?
Scripture — Genesis 38:8-10
Genesis 38:8-10
8 Judah said to Onan, “Go in to your brother’s wife, and perform the duty of a husband’s brother to her, and raise up offspring for your brother.”
9 Onan knew that the offspring wouldn’t be his; and when he went in to his brother’s wife, he spilled it on the ground, lest he should give offspring to his brother.
10 The thing which he did was evil in Yahweh’s sight, and he killed him also.
The Biblical Account
Understanding the Passage
The immediate context suggests that Onan's wrongdoing involved more than the physical act described in the passage. He knowingly accepted the benefits of a relationship with Tamar while deliberately refusing the family obligation associated with it.
In the ancient world, preserving a deceased brother's family line and inheritance was considered an important responsibility. The later Law of Moses established provisions for such marriages, although Onan lived long before those laws were formally given.
Some Christian traditions have interpreted the passage as having broader implications for sexual morality and the deliberate prevention of conception. Other Christian commentators emphasize that the central offense was Onan's selfish refusal to provide an heir for his brother and his exploitation of Tamar.
The narrative particularly stresses Onan's knowledge and intention. He deliberately frustrated the responsibility he had been given while continuing to take advantage of his position.
Conclusion
The clearest lesson of the passage concerns selfishness, deception, and the refusal to fulfill a serious family obligation. Christians differ over its wider implications for sexual ethics, but the immediate narrative condemns Onan for knowingly exploiting Tamar and denying his deceased brother an heir. His actions violated both family duty and the trust placed in him.