Genesis 15 and 17 continue what began in Genesis 12. The general promise of blessing is now given detail, affirmation, and hope for the future.
In Genesis 15 we have the first full description of God’s covenant with Abram. We also find the connection between faith and righteousness. Not only is the foundation for the rest of the Old Testament, 15:6 becomes foundational for the New Testament.
15:6 Abram believed the LORD, and He credited it to him as righteousness.
Following this tremendous statement of faith and righteousness, Abram questions God: “Lord GOD, how can I know that I will possess it?” (15:8). God responds by sealing the covenant with a formal ceremony. Much has written about this section (some controversial).
Normally the weaker king would pass through the dead animals declaring agreement, and if the weaker kind failed to live up to the covenant then he would die, as these animals. In this case, Abram (weaker king) does not, but the presence of God passes through the animals. Thus, Abram fails, God himself would die. Jesus fulfills that covenant when he dies because Abram and his descendants (in fact, all humans) failed to live up tot he covenant.
While Abram received the promise in chapter 15, we find Sarai trying to help Abram and God complete the promise. She gives her slave, Hagar, to Abram, and Hagar becomes pregnant. Within that culture, that child would be considered an offspring; so it would seem that Sarai was “justified” in her actions.
But this backfires for Sarai. “When she [Hagar] realized that she was pregnant, she treated her mistress with contempt” (16:4). That blossoms into Sarai blaming Abram for the problem, and eventually Sarai mistreating Hagar, so much so that Hagar runs away.
While it seems hopeless for Hagar, the Angel of the LORD (Yahweh) finds her and tells her two things, both with mixed promises: 1) return to your mistress: “You must go back to your mistress and submit to her mistreatment” (16:9), and 2) her offspring will receive a promise, too: “I will greatly multiply your offspring, and they will be too many to count” (16:10).
The first part seems strange to our present-day sensitivities. “Submit to mistreatment”? We naturally rebel against such commands. Yet, in that process God is working for her benefit. Notice that God is not condoning the mistreatment, but there is blessing in it. In this case, she will live, and rather well, within Abram’s protective care. In the larger perspective of Scripture, we find that Jesus sets the pattern for “submitting,” yes, to the authorities, which means his eventual death on the cross, but ultimately submitting to God the Father (“but entrusted Himself to the One who judges justly” 1 Peter 2:23). The context helps with understanding God’s work in this, even through the mistreatment.
Household slaves, submit with all fear to your masters, not only to the good and gentle but also to the cruel. For it brings favor if, mindful of God’s will, someone endures grief from suffering unjustly. For what credit is there if you sin and are punished, and you endure it? But when you do what is good and suffer, if you endure it, this brings favor with God.
For you were called to this, because Christ also suffered for you, leaving you an example, so that you should follow in His steps. (1 Peter 2:18-21)
In addition, while her child is not the specific promised child of Genesis 15:1-6, there is still the blessing and promise given to Hagar’s child. But there is the negative side of this promise. Her offspring will multiply greatly, but
His hand will be against everyone, and everyone’s hand will be against him; he will live at odds with all his brothers. (16:12)
Genesis 17 completes the covenant with Abram with two final things: 1) name change, and 2) covenant sign. Abram (“exalted father”) has his name changed to Abraham (“father of a multitude”) signifying the promise of 17:2. While earlier in Genesis, we find the significance of a name mentioned, this is the first time that a man’s name is changed. Note also that Sarai’s name is changed to Sarah. Both mean “princess,” with Sarai being an older form.
While his name change broadens Abraham’s experience of God, the covenant sign, circumcision focuses on the specific nature of that covenant. Whereas the fertility of God’s creation is mentioned for the creatures in the waters above (fish and fowl) (1:22), Adam and Eve (1:28), and Noah (9:1, 7), this is now attached to the promise for Abraham. Until now this was only partially fulfilled in him through Ishmael (17:20), but the promised offspring (Isaac) will carry it to Jacob with several references to the word, 28:3; 35:11; 48:4. Jacob, of course, will have the 12 sons, who become that “great nation.”
It is interesting that circumcision, the sign of the covenant, involves the very organ of Abraham that is involved in fulfilling the covenant. That is, every time he has intercourse with his wife, it is a reminder of the great promises of the covenant that God made with him. As yet, that fulfillment is on the horizon, but God has reassured him that it was true and anticipating that it was already completed by faith. Throughout the centuries that same promise passes from one generation to another until Christ is born (Romans 9:1-5).
The covenant sign of circumcision becomes a hallmark among the descendants of Abraham. Even 2,000 years later, Jews wanted to use circumcision as the deciding factor, trying to force Gentiles who believed in Jesus to be circumcised. Paul stood his ground against this false understanding of circumcision, but even more against a false understanding of the Gospel and faith which receives the Gospel.
But not even Titus who was with me, though he was a Greek, was compelled to be circumcised. (Galatians 2:3)
God has to repeat the promise again, and despite Abraham’s laughter at the idea of Abraham (100 years old) and Sarah (90 years old) having a child, God’s promise is even greater. In Hebrews we read:
By faith even Sarah herself, when she was unable to have children, received power to conceive offspring, even though she was past the age, since she considered that the One who had promised was faithful. Therefore from one man—in fact, from one as good as dead—came offspring as numerous as the stars of heaven and as innumerable as the grains of sand by the seashore. (Hebrews 11:11-12)
Everything is set for Abraham. All of God’s promises are contained in that “offspring,” first Isaac, then Jacob (Israel), and ultimately to the promised offspring, Jesus Christ.
Now the promises were spoken to Abraham and to his seed. He does not say “and to seeds,” as though referring to many, but referring to one, and to your seed, who is Christ. (Galatians 3:16)