The sin in Jesus’ family tree: why the virgin birth of Jesus was necessary

Adoration of the Shepherds / Murillo. virgin birth of Jesus

Adoration of the Shepherds / Bartolomé-Esteban Murillo, ca. 1650

Matthew describes the virgin birth of Jesus from Joseph’s viewpoint in Matthew 2. Have you ever studied the first chapter of Matthew? Most Christians probably skip it. It seems like nothing but a boring genealogy.

But let’s pay some attention. Matthew mentions four women in the first six verses. And all four names recall stories of sin.

Jesus had to be born sinless, live a sinless life, and die as a perfect and unblemished sacrifice. Everyone from Cain and Abel onward has been conceived and born in sin.

And that’s not because they were conceived through sexual union. God planned for that from the beginning. But when Adam and Eve fell into sin, they could only pass on to their children the sin nature they had acquired.

So first, let’s look at those four women to see why Matthew thought them worth mentioning. Then we can see what God did to make sure Jesus would be fit to save us. 


Tamar and Judah. virgin birth of Christ

The Meeting of Tamar and Judah / Tintoretto (between 1555 and 1558)

The story of Judah and Tamar, told in Genesis 38, reads like the story line of the edgiest of soap operas. God took the life of Tamar’s husband, Judah’s oldest son Er, for unspecified wickedness.

It then became the responsibility of the second son, Onan, to provide his brother with an heir by having sex with his widow.

He did not want to, but instead of refusing outright, he withdrew from Tamar so that his semen fell on the ground.

God struck him dead, too. Judah withheld his youngest son Shelah. He told Tamar he was too young, but secretly feared that he would meet the same fate.

Years later, Judah’s wife died. Tamar, living out her widowhood at her father’s house, realized Judah never intended to give her to Shelah, but she was still determined to have children.

Legally, it could only happen through Judah’s family, so she disguised herself as a shrine prostitute, seduced Judah, and bore him twins. One of them, Perez, became a direct ancestor of Jesus.


Rahab was a prostitute in Jericho. When Joshua sent two spies to Jericho, Rahab hid them and helped get them out of town safely. As a reward, they promised her protection.

After the fall of Jericho, she married a man of the tribe of Judah named Salmon. While that sin is not as blatant as Tamar’s, Moses had strictly forbidden Hebrew men from marrying Canaanite women (Deuteronomy 7:1-4), saying they would be a snare and a temptation to the entire society.

New Testament authors praise Rahab, but it violated the law for Salmon to marry her. God graciously made some exceptions to some provisions of the law. Rahab’s right to marry Salmon without penalty must have come as a reward for her service to Israel. Yet it tacitly gave other men permission to marry Canaanites.

Moses had declared that no one born of a forbidden marriage could ever join God’s assembly (Deuteronomy 23:2). Nor could his descendants down to ten generations.


In the well-known story of Ruth, Naomi, along with her husband and two sons, went to Moab to escape a famine. The Bible records nothing of the three men besides their names, but both sons took Moabite wives. We have no reason to suppose that Naomi was an especially godly woman.

Naomi’s husband died. The two sons died without heir. Naomi returned and urged her daughters in law to return to their families. Ruth refused, and vowing to accept Naomi’s God, accompanied her to Bethlehem.

There, Ruth met Boaz and found favor in his eyes because of her devotion to Naomi. To shorten the story, they married, even though Moses had forbidden Israelites to marry Moabites (Deuteronomy 23:3).

Boaz was a godly man, but he was also Salmon and Rahab’s son. The son of a forbidden marriage himself, legally he should not have been regarded as part of the assembly of the Israelites.

For that matter, since the prohibition lasted past ten generations, David himself likewise should have been ineligible because of both Salmon and Boaz. There are some powerful lessons about grace at work in these verses of Matthew!


David covets Bathsheba. Virgin birth of  Jesus

David Covets Bathsheba / Anonymous, 17th-century German

Matthew doesn’t even name Bathsheba. He pointedly refers to Solomon’s mother as the woman who had been married to Uriah.

At a time when David should have been leading his army at war, he decided to stay home.

Then he saw Bathsheba and lusted after her, even though he had his own harem and she was the only wife of one of his best friends.

When she got pregnant, David invited Uriah back from the war, hoping he would have sex with Bathsheba and think the baby was his. David couldn’t get Uriah drunk enough to violate his loyalty to the men who were risking their lives in battle—as David should have been doing.

So David sent him back with a sealed letter instructing his general to see that Uriah fell in battle. Then he married Bathsheba, still hoping no one would notice. God did and sent a prophet to scold him.

What does all this sin have to do with Jesus?

The annunciation / El Greco. virgin birth of Jesus

The Annunciation / El Greco

Most of us today would not criticize Salmon for marrying Rahab or Boaz for marrying Ruth.  But surely no one can defend Judah’s relationship with Tamar or David’s with Bathsheba.

And of course Scripture records the gross sin of other men on the list, including other heroes of the faith.

The stories in the Old Testament amply show humanity’s need for redemption. Who can rescue us from this unending pit of sin? Only a perfect, sinless redeemer.

Satan became the god of this world when Adam decided to obey him instead of God. The redeemer would have to be a man who would choose to obey God rather than Satan. Who else would be qualified except God himself becoming that man?

In other words, the redeemer would have to be both fully human and fully God. How could this combination possibly happen without a fatal contamination on the human side by sin? How could sinless God unite himself with sinful humanity to redeem the world?

The only correct answer to the second question it that even omnipotent God cannot accomplish that using ordinary sexual union. God’s omnipotence means that he can do anything that can be accomplished by power. Power cannot perform a self-contradiction.  It is self-contradictory to unite sinlessness with sin without polluting it.

How the virgin birth of Jesus happened

Annunciation / Fra Angelico. virgin birth of Jesus

Annunciation / Fra Angelico

If a person conceived in the usual way would necessarily be born sinful, then the redeemer would have to be conceived in an unprecedented way. Thus the virgin birth of Jesus.

God couldn’t make a new man from the dust of the earth, as he made Adam. He no longer had title to the dust of the earth. Adam had turned it over to Satan.

Besides, as Jesus said at the beginning of John 10, whoever enters the sheep pen by any means other than the doorway is a thief and a robber.

The legal doorway into human life on Earth is through a woman’s womb.

Conception usually results from the union of sperm from a sinful man with an egg in a sinful woman. And so it the embryo is born sinful. God created a special embryo, with no genetic material from either Joseph or Mary, and implanted it in her uterus while she was still a virgin.

God could unite his Spirit with this newly created and sinless human embryo. God’s plan didn’t require the virgin birth of Jesus because sex is somehow immoral. Sex was his idea in the first place. He required it as evidence of Jesus’ supernatural conception. That conception led to an entirely ordinary birth, life, and death as a human.

The Spirit of God united himself to this newly created sinless humanity without polluting himself. That’s how Jesus became both fully God and fully human. From that unity, God’s power could and did accomplish his redemptive purpose.

Let us rejoice at the wisdom and the power God exerted to save us from our own worst instincts.

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