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Onanism – What is it? Is it a sin?

Onanism – What is it? Is it a sin?
Redemption Theology

TL;DR:

“Onanism” is often misunderstood as referring to masturbation, but that meaning comes from a misreading of Genesis 38. Onan’s sin was that of deliberately refusing to provide an heir for his deceased brother while exploiting his sexual responsibility for personal reasons.

what does the bible say?

The term Onanism comes from the biblical figure Onan in Genesis 38:8–10. The later association of Onanism with masturbation is the result of a misinterpretation of Genesis 38, not the meaning of the passage. Scripture identifies Onan’s sin as deliberate disobedience against his responsibility as the husband of his brother’s widow.

In Genesis 38, Onan was to provide an heir for his deceased brother by fathering a child with his brother’s widow. This duty existed to preserve the family line and to protect the widow by giving her legal standing and provision. Though later codified in Israel’s law (Deuteronomy 25:5–10), this obligation was already recognized as morally binding. Onan agreed outwardly to the arrangement but deliberately acted to avoid conception while still taking sexual advantage of the situation. His actions were calculated and self-serving.

Because Onan refused to raise offspring for his brother and deliberately undermined the responsibility God placed upon him, God judged him with death. His sin was exploitation, rebellion against God’s command, and a hard-hearted refusal to love his neighbor. Using Onan’s story to condemn masturbation or specific birth-control methods goes beyond what the passage teaches.

from the old testament

  • At the time of Genesis 38, there was an established family responsibility that required a close male relative to provide offspring for a deceased brother through his widow. This duty ensured the continuation of his brother’s family line and protected the widow from poverty and social vulnerability. While this obligation was formally codified later in Deuteronomy 25:5–10, Genesis shows that the expectation already existed in Israel’s early history.
  • Genesis 38 explains what Onan did and why it was sinful. Judah, Onan’s father, told 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” (Genesis 38:8). Onan went in to her, but Scripture says, “whenever he went in to his brother’s wife he would waste the semen on the ground, so as not to give offspring to his brother” (Genesis 38:9). Onan deliberately hindered conception but took advantage of the situation by still having sexual relations with his brother’s widow.
  • Onan’s actions were “wicked in the sight of the LORD, and he put him to death also” (Genesis 38:10). The focus was not on the wasted semen or the fact that Onan was engaging in a primitive form of birth control, but on Onan’s intentional, heart-level rebellion. He outwardly complied while inwardly refusing to obey, exploiting his brother’s widow for his own sexual gratification while denying her the protection that God’s design required.

from the new testament

  • Though the passage about Onan is in the Old Testament, the sin of Onan–rebellion against God–-is one that is present throughout Scripture. In pointing out the hypocrisy of the Pharisees, Jesus said, “Well did Isaiah prophesy of you, when he said: ‘This people honors me with their lips, but their heart is far from me; in vain do they worship me, teaching as doctrines the commandments of men’” (Matthew 15:7-9).
  • Ananias and Sapphira, attempting to deceive God (as if that were possible!), pretended to donate the full proceeds from a sale of property when they were actually holding back some. Peter noted that their sin was lying to the Holy Spirit (Acts 5:3-4). As with Onan, death was their punishment (Acts 5:5, 5:10).

implications for today

Onan’s story teaches a timeless truth: God desires obedience from the heart, not merely outward pretense. While the command given to Onan was specific to his time and circumstance, the selfishness of his heart still happens today. Every time we knowingly refuse to obey God, we are like Onan. If you’re lying on your taxes, shrugging off your own sexual immorality, presenting one face at church on Sunday but a very different one Monday through Saturday—you’re rebelling against the God you claim as Father.

Our sin brings death to each one of us (Romans 5:12; 6:23). While Onan was judged right away with death, all of us would also die because of our sin—except for Jesus. But as the apostle John wrote, “No one who abides in him [Jesus] keeps on sinning; no one who keeps on sinning has either seen him or known him” (1 John 3:6). Christ is ready to forgive, though, when you repent. Children of God we can confess their sin and be forgiven (1 John 1:9). Avoid the sin of Onan, rebellion against God, by abiding in Christ (John 15).

understand

  • Onan’s sin was refusing his duty to provide an heir while acting selfishly.
  • Onanism is not about masturbation; his guilt was rebellion, not semen spilling.
  • The story of Onan teaches God values heartfelt obedience over outward compliance.

reflect

  • How do you see your own heart—where are there areas of hidden rebellion?
  • When faced with responsibilities toward others, how do you assess whether you are acting out of love or self-interest like Onan?
  • How can you cultivate obedience from the heart rather than just outward compliance in your life?

engage

  • Why do we sometimes outwardly follow God’s commands while our hearts resist, and how can we help each other guard against this?
  • How does understanding Onan’s sin clarify the difference between moral duty and selfish exploitation of others?
  • What practical steps can we take to encourage authentic, heart-level obedience to God?

More Resources

Sexuality Is masturbation a sin according to the Bible?

Is masturbation a sin according to the Bible?

While the Bible doesn’t explicitly mention masturbation, it speaks against lust and self-gratification and instead calls us to sexual purity and self-control. Pursuing God’s design for sexuality is where true gratification is found.
Sexuality Are wet dreams / nocturnal emissions sinful?

Are wet dreams / nocturnal emissions sinful?

Wet dreams themselves are a normal physical process and not sinful. However, if they are fueled by lustful thoughts or habits, the heart and mind may be improperly focused.
Sexuality Can a person ever masturbate without it being a sin?

Can a person ever masturbate without it being a sin?

Masturbation, by nature of what it is, is considered to be sinful. Believers, even married spouses who are apart, are called to pursue purity and trust God to meet their needs.
Life What does the Bible say about birth control?

What does the Bible say about birth control?

Apart from one narrative, the Bible does not specifically discuss birth control. Children are seen as a gift from the Lord, and a couple needs wisdom to determine what sort of family planning they should consider.