In the Beginning:
The Book of Genesis

Lesson 12 The Birth of Isaac
the book of Genesis 20:1—21:34

Revised Standard Version Catholic Edition (RSVCE)*
New American Bible Revised Edition (NABRE)*
Catechism of the Catholic Church
ex libris (in our library)
glossary for the book of Genesis
cross references in the book of Genesis
next lesson: God Tests Abraham

This material coordinates with Lesson 12 on pages 67–72 in the study book In the Beginning: The Book of Genesis.

“And God saw everything that he had made, and behold, it was very good. And there was evening and there was morning, a sixth day. Thus the heavens and the earth were finished, and all the host of them.  And on the seventh day God finished his work which he had done, and he rested on the seventh day from all his work which he had done.”—the book of Genesis 1:31—2:2

welcome to our in-depth study of the book of Genesis
We invite interested groups and individuals to check out the sample first lesson from this 28-lesson Turning to God’s Word Catholic Bible study. These online study pages link to free lesson videos, an online glossary, and a list of cross references in the biblical text. Other study aids include maps, charts, illustrations, additional commentary, and prayers based on the primary Scripture in each lesson. In the Beginning: The Book of Genesis has been granted an imprimatur and can be purchased from our website shop. If you have a Bible-related question or comment, click on one of the “ask us your question” or “what do you think” buttons on any online study page.

open with prayer
It’s always wise to begin any Bible study with prayer, whether reading the Scriptures alone or meeting with others in a discussion study group. You can pray using your own words or use one of the opening prayers on our website. We especially like the following:

Lord Jesus, you promised to send your Holy Spirit
to teach us all things.
As we read and study your word today,
allow it to touch our hearts and change our lives. Amen.

let’s review—the book of Genesis 19:1–38
Lesson 11 The Destruction of Sodom & Gomorrah tells the familiar story of how God sends fire and brimstone to destroy Sodom and Gomorrah, two cities located on the shores of the Dead Sea. The cause of the LORD’s anger is seen as the wickedness of the cities’ inhabitants. One interesting detail that rarely receives any attention is that the future sons-in-law of Abraham’s nephew Lot, who live in Sodom, apparently join with others in the city who plan to harm Lot’s visitors (who’ve been sent by God.) The future sons-in-law refuse to leave Sodom with Lot’s family, and Lot’s wife turns into a pillar of salt when she turns around to see the destruction wrought by God. Another detail that’s often overlooked is that after escaping from Sodom, Lot’s daughters arrange to become pregnant by their father, establishing the peoples who come to be known as the Moabites and the Ammonites.

map notes—when was Hagar sent away, and where did she go?
There are a number of differences between the two stories of Hagar being sent away, not the least of which is a discrepancy about the location where she encounters an angel. This occurs near either Beer-lahai-roi, in the book of Genesis 16:1–16, or Beer-sheba, in the book of Genesis 21:14–21. A well figures in both accounts, at locations in roughly the same geographical region. The map shows the wilderness area to which Hagar and Ishmael are sent away after Isaac’s been weaned and Isaac’s mother Sarah perceives that Ishmael poses a threat to Isaac’s future as Abraham’s heir. What other examples of familial rivalry have previously been recorded in the book of Genesis? While the two accounts of Hagar being sent away differ significantly, they’re indicative of the diptychs that appear throughout the book of Genesis. Click on the the map (right) to enlarge it. The original map is on page 71 in the study book In the Beginning: The Book of Genesis. 

what’s God saying? (16:43)
In the video for this lesson, Turning to God’s Word author Matthew Phelps discusses how to approach the diptychs in the first book of the Old Testament. In addition to similar stories about Hagar, the twelfth chapter in the book of Genesis records a story about Abraham and Sarah in Egypt that’s mirrored in the twentieth chapter by a story of their stay in Gerar. Since the intent of Scripture is to disclose something that God wishes to reveal about himself, historically precise details may not play into all biblical writing, especially the older sections of the Bible. A diptych uses more than one version of a story to demonstrate how the same event can show us more than one thing about God. The videos for this study are being redone and will be posted as they become available. The original videos will remain accessible until then.


The Scripture ranges for the videos that accompany this Catholic Bible study from Turning to God’s Word match the Scripture ranges for the sets of questions in In the Beginning: The Book of Genesis. You can follow along with the video overview as Turning to God’s Word author Matthew Phelps discusses Lesson 12, “The Birth of Isaac,” on pages 67–72 in the study book.

let’s look at similar stories in the book of Genesis
Anyone who takes Scripture study seriously quickly learns that many contradictory versions of the same events occur on a fairly regular basis. This starts right away with two versions of Creation in the book of Genesis; the parallel versions—often called diptychs—continue throughout the first book of the Old Testament.

?  List all the differences you see between the story of Hagar being sent away that appears in the sixteenth chapter in the book of Genesis, and the story in the twenty-first chapter in the book of Genesis.
?  What do you consider the most significant difference?
?  What reasons can you suggest for why both of these accounts are included in Sacred Scripture?
?  How does the story of Abraham and Sarah’s stay in Gerar resemble the story of their stay in Egypt recorded in the book of Genesis 12:10–20?
?  What are the main differences between these two stories?
?  Consider what might explain why both of these accounts are included in Scripture.
?  What are some modern examples of differing accounts of an event that provide complementary information yet still allow for both versions to be regarded as true?

prophet—you could look it up in our archives
Although Abraham rarely is described as a prophet, in the book of Genesis 20:7 he nevertheless is the first person so identified in the Bible. To learn how the present-day meaning of the word “prophet” differs from the original meaning, read Lost in Translation, an online column in which Turning to God’s Word author Matthew Phelps helps readers connect with ideas expressed in the original languages of the Scriptures. New Lost in Translation entries are posted on Mondays, and past entries are archived on our website. Contact us if you’d like to receive Lost in Translation by email every week.

more about Abraham as a prophet
Even though Abraham is called a prophet by God, he still made a mistake regarding Abimelech’s character. Despite Abraham’s failure to look into the future and make an accurate prediction, something we assume that all prophets can do, Abimelech’s fate still remains in Abraham’s hands. This suggests something important about the role of a biblical prophet. Unless Abimelech restores Sarah to Abraham posthaste, Abimelech is going to be toast. Abimelech’s life depends on whether Abraham prays to God on Abimelech’s account. In this particular instance, Abraham’s role as a prophet appears to consist of the ability to control life and death in a very limited way. Thus Abraham not only can be considered able to speak to God but also able to speak for God specifically concerning Abimelech’s fate. The Turning to God’s Word two-part Catholic Bible study Thus Says the LORD: God Speaks Through His Servants the Prophets—Volume I: A Kingdom Divided and Volume II: Restoration & Redemption offer an in-depth look at the role of the biblical prophets.

ethnic purity is a big deal in the book of Genesis
The nineteenth chapter in the book of Genesis records the racy story of Lot’s daughters having children as a result of sex with their own father. The biblical text goes to some length to remove agency from Lot, and the writer is fairly negative about the resulting progeny. This indicates that even in the ancient world, incest was frowned upon. The twentieth chapter stresses that Abraham and Sarah are half-brother and half-sister. Apparently that they are fairly close blood relatives doesn’t preclude their marriage and doesn’t carry with it the same taboos as Lot fathering children by his daughters.

Preservation of ethnic identity and purity in the family line remain important considerations in regard to the difference between Isaac and Ishamael. Ishmael’s mother is an Egyptian, which makes her a descendant of Ham, while Isaac’s mother is a Hebrew descendant of Shem. The book of Genesis 9:18–27 records Noah’s son’s reactions to their father’s shameful nakedness. Ham was the son who misbehaved. Although the bulk of the penalty fell on Canaan, none of Ham’s descendants are joining in the covenant inheritance given to Abraham by God.

the best Catholic commentary about Scripture
To find out more about how Church teaching is supported by Scripture passages in In the Beginning: The Book of Genesis, check out the Index of Citations in the Catechism of the Catholic Church. Links to the primary Scripture passages in the lesson (Revised Standard Version Catholic Edition [RSVCE*]) and relevant paragraphs in the Catechism are provided here. Not every passage in the biblical text for this Catholic study is referenced in a Catechism paragraph, however.

the book of Genesis 21:1–2—paragraph 489
the book of Genesis 21:17—paragraph 332

ways our glossary might prove helpful
In addition to providing extra information about geographical locations, our glossary also points out persons or places mentioned in the biblical text under more than one name or more than one spelling. If you can remember a name but aren’t sure in which lesson it shows up, you can find it in the glossary, which lists every proper noun that appears in the biblical text for every lesson in In the Beginning: The Book of Genesis.

to learn more, read more Scripture
If you’re having difficulty with a particular passage of Scripture, it can be helpful to read the relevant cross references—but looking these up can take time. To make that easier, we’ve compiled the cross references from the Revised Standard Version Second Catholic Edition (RSV2CE)—the translation that we reprint in our study books. A link to that list can be found at the top of every online study page; the list features links to cross references in the primary biblical text in the study book In the Beginning: The Book of Genesis.

don’t forget about our indexes & extra online material
If you’re trying to locate information about a specific Scripture passage, you can look it up in the index at the back of the study book or sample lesson. If you want to find a particular commentary, you can look up its title in the topics index. To learn more about another book of the Bible for which there’s a Turning to God’s Word study, visit the online study directories to read the commentaries and watch any accompanying videos. Finally, if you have a question or would like to make a comment about any of our studies, you can use one of the “ask us your question” or “what do you think” buttons to email our authors.

ex libris—Church documents & books about religious topics
Link to magisterial documents referred to in our Bible studies at ex libris—magisterial documents. This listing includes significant recent encyclicals as well as a number of historical Church documents. Recommended books related to Scripture study can be found at ex libris—main bookshelf.

wondering how to pronounce some of these words?
The following link is to a reading from the New International Version (NIV) Bible. To listen, open the link and click on the audio icon above the printed text. Although not taken from the translations used in our study materials, the NIV reading provides an audio guide to pronunciation of words in this lesson’s primary biblical text. A close online version of the translation of the Bible used in Catholic liturgy in the United States as well as an audio guide for daily Mass readings for the current month can be found on the website of the United States Conference of Catholic Bishops (USCCB).

the book of Genesis 20:1—21:34 (NIV)

round black doveclose with Bible-based prayer related to this lesson
Many of our Catholic study groups like to conclude their discussions with a prayer based on the scriptural focus of their lesson, and some participants include Scripture-specific prayer in their individual study. If you’re uncomfortable composing your own Bible-based prayers, you can follow our four easy steps. If you prefer, you can use the following prayer based on this lesson’s text from the book of Genesis.

O God, you brought about the birth of Isaac
under circumstances that humanity considers
nothing short of miraculous.
Give us the grace to trust in your loving care for us
even when we’re tempted to become impatient
while waiting for a sign that you hear our prayers.
We ask this in the name of Jesus Christ,
who trusted in your love enough to face death
in order to give men and women
the possibility of eternal life. Amen.

Lesson 13 God Tests Abraham—the book of Genesis 22:1—23:30
Lesson 11 The Destruction of Sodom & Gomorrah—the book of Genesis 19:1–38

you also may like our study of the book of Exodus
You Shall Have No Other Gods: The Book of Exodus, a 28-lesson Catholic Bible study with an imprimatur, provides an in-depth look at how significant events in biblical history that occurred thousands of years ago to descendants of Jacob remain relevant and even critical for present-day Christians to understand. The deliverance of the Hebrews from slavery in Egypt and the giving of Ten Commandments are examined along with the development of Moses’ relationship to God. Click on the book’s cover to view a sample lesson.

start a Turning to God’s Word Bible study
Thank you for your interest in our study In the Beginning: The Book of Genesis. Information about beginning a Turning to God’s Word Catholic Bible study can be found at start a Bible study. Tami, Matthew, and I are available to answer questions and offer support. Contact us if you’d like to start a Turning to God’s Word study or have your schedule listed with other TtGW study groups on our website. —Jennifer

*There are seven deuterocanonical books in the Old Testament—the Books of Tobit, Judith, Wisdom, Sirach, Baruch, and First and Second Maccabees, as well as some passages in the Books of Esther and Daniel. Protestants usually refer to these works as “apocryphal,” a word that means “outside the (Protestant) canon” because they’re excluded from most Protestant Bibles. The word “deuterocanonical” means “second canon”; Catholics use that word to refer to any section of the Catholic Old Testament for which there are no extant, or existing, Hebrew manuscripts. All of the deuterocanonical books appear in the Septuagint, the earliest remaining versions of which date to the 1st century B.C. This Greek translation of the Old Testament was in common use by Jews at the time of Jesus. Learn more by reading How Do Catholic & Protestant Bibles Differ?

Turning to God’s Word printed Bible studies use the 2006 Revised Standard Version Second Catholic Edition (RSV2CE) translation for all Scripture references except those to the Psalms, which are taken from The Abbey Psalms and Canticles, prepared by the Benedictine monks of Conception Abbey and published in 2020 by the United States Conference of Catholic Bishops (USCCB). All Scripture links for the online study pages for In the Beginning: The Book of Genesis are to the 1966 Revised Standard Version Catholic Edition (RSVCE) translation. The New International Version (NIV) audio recordings follow the same chapter and verse numbering as the RSV Catholic translations, but the NIV translation doesn’t include the deuterocanonical books and passages.

The 1966 RSVCE uses archaic pronouns and verb forms such as “thee,” “thou,” “didst” in the Psalms and in direct quotations attributed to God. The 2006 RSV2CE replaces these with more accessible English. The few significant translation changes in the RSV2CE include rendering almah as “virgin” in the Book of Isaiah 7:14 and restoring the term “begotten” in the Gospel According to John 3:16.

Numbering varies for some passages in this Bible study. Turning to God’s Word studies (print and digital) follow the numbering in the Revised Standard Version Catholic translations (RSV2CE and RSVCE). Discrepancies in the New American Bible Revised Edition (NABRE) are noted in the Index of Scripture Citations in the study book and the online sample.

You can learn more about the Psalms by viewing a sample lesson from the Turning to God’s Word Catholic Bible study Sing a New Psalm: Communicating with God Through the Prayers of the Church—Volume I: Lauds & Vespers. The second part of that study, Sing a New Psalm: Communicating with God Through the Prayers of the Church—Volume II: Vigils, Day Prayer & Compline, is scheduled for publication in 2025. Some verse numbers may vary in different translations of the Psalms.