However, among these, the most important became Judah, the son of Leah, because, before he died, Jacob said that Judah would become the leader of his people and, indeed, the Jews of today have that name because they are of the Tribe of Judah.
Judah first had three sons: Er, Onan and Shelah. Judah took a wife for Er named Tamar. However, Er was wicked and God killed him.
In those days, there was a custom which still exists in Arab countries and in other countries of the Middle East that when a man dies and leaves a widow, his next surviving brother is supposed to marry the widow and become her husband.
Accordingly, Onan was obliged to marry Tamar, the widow of Er.
However, in such a case, the eldest son from this marriage was considered to be not the son of the new husband, but rather the son of the husband who died. In this way, it was thought that the seed of the deceased man would be carried forward into the coming generation.
Onan did not like this. He did not want a child from Tamar to be the child of his deceased brother, Er. For this reason, when Onan had sex with Tamar, he pulled out at the last moment. Onan did not allow his seed to go into Tamar. Instead, he spilled his seed upon the ground. Onan did this because he not want Tamar to become pregnant.
God saw this and saw that Onan had disobeyed the will of God. This seed is not supposed to go into the ground. Rather, it is intended by God to go into a woman. Therefore, God struck Onan dead, too. This made Tamar a widow a second time.
The third son was Shelah. However, Shelah was still a young boy, too young to be married. Judah was afraid that his third son Shelah would die, too. Therefore, he told Tamar to go back to her father's house and wait there and when Shelah became old enough, Judah would marry Tamar to him.
Tamar went back to her father's house and waited.
After the passage of some time, Tamer noticed that Shelah had grown up. Nevertheless, Tamar had not been given to Shelah as a wife. Judah had not kept his promise. Tamar was tired of waiting.
Tamar found out that Judah was going to go to Timnath to shear his sheep. She took off her widow's garment and instead put on a veil to cover her face. She went and sat by the road to Timnath.
Judah came walking by. Because the face of Tamar was covered, he believed that she was a prostitute. Judah did not know that actually this was his daughter-in-law Tamar. He asked her what was her price for sex. She asked him how much he would give her. He said that he would send her a kid from his flock of sheep. She then asked him to give her something as security for this promise. She asked him for his signet, his bracelets and his staff. Judah agreed to this. He gave Tamar his signet, his bracelets and his staff and then had sex with Tamar. Tamar became pregnant.
After the sex was finished, Judah left. Tamar left also. She took off her veil and put back on her widow's clothing.
Later, Judah sent a man with a kid from his flock of sheep to give to the woman he had seen by the road and to recover his signet, his bracelets and his staff. However, when his messenger came to that spot, no woman was there. He asked the men of that area what had happened to the prostitute who had been sitting there. Those men said that there had been no such woman. There had never been a prostitute in that place. Judah was dismayed by this development.
Three months later, word came to Judah that his daughter-in-law had been like a prostitute and was now pregnant. Judah ordered that Tamar be brought before him to be burned up.
When Tamar was brought, she said to Judah, "The man who has made me pregnant is the owner of these things." Then Tamar produced the signet, the bracelets and the staff which belonged to Judah.
With that, Judah acknowledged that these things were his and said that she was more righteous than he because he had not kept his promise to her by not giving Tamar to Shelah as a wife. Therefore, Tamar was spared.
Tamar gave birth to twins. The name of these twins were Pharez and Zarah.
The son of Pharez was Hezron. The son of Hezron was Ram. The son of Ram was Amminadab. The son of Amminadab was Nahshon. The son of Nahshon was Salmon. The son of Salmon was Boaz. The son of Boaz was Obed. The son of Obed was Jesse. The son of Jesse was David. The son of David was Solomon. The son of Solomon was Rehoboam. The son of Rehoboam was Abijah. The son of Abijah was Asa. The son of Asa was Jehoshaphat. The son of Jehoshaphat was Jehoram. The son of Jehoram was Uzziah. The son of Uzziah was Jotham. The son of Jotham was Ahaz. The son of Ahaz was Hezekiah. The son of Hezekiah was Manasseh. The son of Manasseh was Amon. The son of Amon was Josiah. The son of Josiah was Jeconiah. The son of Jeconiah was Shealtiel. The son of Shealtiel was Zerubbabel. The son of Zerubbabel was Abiud. The son of Abiud was Eliakim. The son of Eliakim was Azor. The son of Azor was Zadok. The son of Zadok was Achim. The son of Achim was Eliud. The son of Eliud was Eleazar. The son of Eleazar was Matthan. The son of Matthan was Jacob. The son of Jacob was Joseph and Joseph was the husband of Mary the mother of Jesus.
So, from the illicit relationship between Tamar and Judah, three of the most important people in history were born: David, Solomon and Jesus.
This story can be found in the Bible in Genesis 38 and 49, Matthew 1 and Luke 3.
This story is important in many ways. It establishes the genealogy of the Jewish race, because it is fair to say that all of the Jews today are descended from Pharez and Zarah, the two bastard twin sons of Tamar. (The only other surviving son of Judah was Shelah, about whom nothing more is said in the Bible.)
Onan, the second husband of Tamar, has provided us with a word in our language. That word is Onanism. It means withdrawal during sex.
Onan was struck dead by God because he practiced birth control. Onan pulled out because he did not want Tamar to become pregnant. Because he did that, God killed Onan. When the Pope says that birth control is prohibited by God, he is referring to the story of Tamar and Onan.