Why did God kill Onan according to Genesis 38?

Genesis 38 presents a complex and somewhat controversial narrative involving Judah and his sons, including Onan. The story is set within the broader context of the patriarchal history of Israel, specifically focusing on the lineage of Judah, one of the twelve sons of Jacob. Understanding why God killed Onan requires a careful examination of the text, cultural context, and theological implications.

The narrative begins with Judah, who marries a Canaanite woman named Shua and has three sons: Er, Onan, and Shelah. Judah arranges for his firstborn, Er, to marry Tamar. However, Er is described as wicked in the sight of the Lord, and God puts him to death (Genesis 38:7). The text does not specify the nature of Er’s wickedness, but it sets the stage for the levirate marriage custom that follows.

In ancient Near Eastern culture, levirate marriage was a practice designed to preserve a deceased man's lineage and provide for his widow. According to this custom, if a man died without leaving a male heir, his brother was obligated to marry the widow and produce offspring in the deceased brother's name. This practice is later codified in Deuteronomy 25:5-6, which states: "If brothers are living together and one of them dies without a son, his widow must not marry outside the family. Her husband's brother shall take her and marry her and fulfill the duty of a brother-in-law to her. The first son she bears shall carry on the name of the dead brother so that his name will not be blotted out from Israel."

After Er's death, Judah instructs Onan to fulfill this duty and marry Tamar to produce offspring for his deceased brother. Genesis 38:8-9 recounts: "Then Judah said to Onan, 'Go in to your brother's wife and perform the duty of a brother-in-law to her, and raise up offspring for your brother.' But Onan knew that the offspring would not be his. So whenever he went in to his brother's wife, he spilled the semen on the ground, lest he should give offspring to his brother."

Onan's actions reveal a deliberate refusal to fulfill his levirate duty. By spilling his semen on the ground, Onan ensures that Tamar does not conceive, thereby preventing the continuation of his brother's lineage. This act of contraception is not merely a personal preference but a direct defiance of a culturally and religiously significant obligation. Genesis 38:10 states: "And what he did was wicked in the sight of the Lord, and he put him to death also."

The key to understanding why God killed Onan lies in the nature of his offense. Onan's sin was multifaceted:

1. Disobedience to Cultural and Familial Duty: Onan's refusal to provide offspring for his deceased brother was a violation of the levirate marriage custom. This duty was not just a familial obligation but a cultural and religious imperative to ensure the continuity of the family line and the inheritance of land, which was crucial in Israelite society.

2. Selfishness and Greed: By not producing an heir for his brother, Onan potentially stood to gain a larger share of the inheritance. If Tamar bore a son, that son would inherit Er's portion, reducing Onan's inheritance. Onan's actions reflect a selfish desire to protect his own interests at the expense of his familial responsibilities.

3. Deception and Exploitation: Onan's repeated sexual relations with Tamar, while intentionally preventing conception, constituted a form of deception and exploitation. He used Tamar for his own sexual gratification without honoring the commitment to raise offspring for his brother. This exploitation of Tamar's vulnerability was a grave injustice.

4. Defiance of Divine Will: Ultimately, Onan's actions were seen as defiance against God's will. The continuation of the family line and the fulfillment of the levirate duty were integral to God's covenantal promises to Abraham, Isaac, and Jacob. By refusing to fulfill this duty, Onan was acting against the divine plan for the preservation and proliferation of the chosen people.

The severity of Onan's punishment reflects the seriousness of his offense in the eyes of God. It underscores the importance of obedience to divine commands, the sanctity of family responsibilities, and the ethical treatment of others. Onan's death serves as a stark reminder of the consequences of selfishness, deception, and disobedience.

The story of Onan also has broader theological implications. It highlights the theme of justice and divine retribution, demonstrating that God holds individuals accountable for their actions. Furthermore, it underscores the importance of faithfulness to God's commands and the ethical treatment of others within the community.

In Christian theology, this narrative has often been interpreted in various ways. Some have viewed it as a condemnation of contraception, while others see it more broadly as a lesson in obedience and the ethical treatment of others. It is essential to approach the text with a nuanced understanding, recognizing the cultural and historical context while drawing out the timeless principles of justice, responsibility, and faithfulness.

In conclusion, God killed Onan because his actions were wicked in multiple dimensions: he disobeyed a significant cultural and religious duty, acted out of selfishness and greed, deceived and exploited Tamar, and ultimately defied God's will. This narrative serves as a powerful reminder of the importance of obedience, justice, and the ethical treatment of others, principles that resonate throughout the biblical text and continue to be relevant in our lives today.