Genesis 22 is about God testing Abraham to see whether he truly feared God and would thus obey Him at all costs. When Abraham passed the test God swore by Himself that He would surely fulfill the terms of the Abrahamic Covenant (verses 16-18). The significance of this event is highlighted in the book of Hebrews to encourage believers who are tempted to give up their faith in Christ. We are told that God's promise by itself is trustworthy enough. But to demonstrate how unchangeable His purpose is, God guaranteed the promise with an oath, rendering it doubly certain that He will surely fulfill everything He promised in the Abrahamic Covenant (Hebrews 6:13-18).
In the test God asked Abraham to sacrifice Isaac, whom God had insisted to be his heir, through whom the great nation God promised would come. The fact that child sacrifice is abominable to God is beside the point, as God was only testing Abraham to see how he would respond. So when Abraham took the knife to slaughter his son God stopped him. Abraham must have had considered the apparent contradictory intentions of God. For if Isaac was to be sacrificed, how then could he be his heir?
Hebrews (11:17-19) explains that Abraham believed that after he had sacrificed Isaac, God would raise him from the dead. This presupposes an unshakable faith in God that He will keep His word no matter how impossible it may seem to be. In this case, if God said Isaac would be Abraham's heir, it would surely come to pass, even if Isaac had been sacrificed. On this basis Abraham believed that God would raise Isaac form the dead, though there is no evidence that Abraham had ever heard of such a thing.
When did Abraham learn this kind faith? We read that he had twice lied about his wife being his sister, each time to save his own life (Genesis 12:10-20; 20:1-18). He did not have this level of faith prior to Genesis 20. A coherent reading of the narrative of Genesis 12-22, bearing in mind that the plot climaxes in Genesis 22, will show that God Himself, beginning with Genesis 12, was preparing Abraham to pass the ultimate test of obedience in Genesis 22. For the plot of a narrative “functions to transform a chronicle or listing of events into a schematic whole by highlighting and recognizing the contribution that certain events make to the development and outcome of the story” (Polkinghorne 1988: 18-19). How then do the events narrated in Genesis 12-21 contribute to the outcome in Genesis 22?
When Abraham responded to God's call to leave his homeland, his father's household and his relatives, God did not say that the promised great nation would come from Abraham's biological descendants. The narrator sums up Abraham's response like this: “So Abram went forth as the LORD had spoken to him; and Lot went with him” (Genesis 12:4). Why qualify that his nephew Lot went with him, unless this is crucially significant? For this information is also included in the very next verse, which recounts that Abraham took with him his wife Sarah, his nephew Lot and all his possessions.
Recall that Abraham was supposed to leave his father's household and his relatives. Hence he was not supposed to take Lot with him. Why then did he do it? The clue is already given in Genesis 11:27-32, which sets the stage for Genesis 12 onwards. For it highlights the barrenness of Sarah (Abraham's wife), which means he had no son (yet), and the death of Lot's father (Abraham's brother), which means Lot could potentially become Abraham's heir (cf. Steinberg 1993: 50-52). This explains why Abraham took Lot with him. Abraham had enough faith to leave his homeland not knowing where he was going, but not enough faith to believe that God could give him descendants of his own to form the great nation God promised.
His obedience was thus incomplete as his faith was still infantile. It was only when Lot left him (13:1-13) that Abraham finally fulfilled his part completely, which also meant Abraham’s hope that Lot might become his heir was dashed. Accordingly God specifically promised that Abraham's descendants would be very many and that they would possess Canaan (13:14-18). Through God's protection and blessing in his embarrassing encounter with the Pharaoh when he lied about his wife being his sister (12:10-20), and later in his dangerous expedition to rescue Lot (14:1-16), Abraham's faith would have grown.
In Genesis 15, the still childless Abraham proposed to God that his chief slave Eliezer be his heir. Only then did God reveal to him that his heir would come from his own body. When God further said that He would greatly multiply Abraham's (own) descendants, “Abraham believed in the LORD, and it was reckoned to him as righteousness” (verse 6). This signals an increase in faith.
When God further promised that Abraham's (own) descendants would possess Canaan, Abraham asked for a tangible assurance. God responded with the ceremony in which He unilaterally and unconditionally “signed” the Abrahamic Covenant. As pointed out in Hebrews, God's promise by itself would have sufficed. In formally “signing” the covenant after the manner of how human beings covenanted with one another, God condescended to the human level to help Abraham further believe in Him and His promise.
When Sarah gave her maid Hagar to Abraham so that he could have an heir through her, Abraham accepted it because it made sense to him, as this would fulfill God's condition that his heir would come from his own body (Genesis 16:1-4). After all it was Sarah who took the initiative and what she did was in accordance with the custom of the time (Hamilton 1990: 444-45). And God did not say (not yet!) that his heir had to come from Sarah's body. Why not (yet)? Recall that Sarah was barren. So it would take greater faith to believe it.
Hagar bore Abraham a son, Ishmael. It was only when Ishmael was a teenager and Abraham was too old to father any children that God said to Abraham that his heir was to come from Sarah's body as well (Genesis 17:15-21). Since Abraham protested, pleading with God that Ishmael be his heir, it shows that hitherto Abraham did not have the faith to believe God for what is humanly impossible. Nevertheless God insisted that Sarah's son, to be named Isaac, would be his heir. God even promised that she would bear Isaac “at this time next year.” There is no indication that Abraham believed in this promise (not yet!).
Looking at Abraham’s faith development, it makes sense why God did not reveal to Abraham at the beginning that his heir would be his own son through Sarah. For he obviously did not have the faith to believe that Sarah could bear him a son, and thus may not have responded to God's call to leave his homeland. The plot indicates that God revealed His intention stage by stage according to Abraham's level of faith, which God was helping him grow gradually.
When God came to reassure Abraham in Genesis 18 that “at this time next year ... Sarah your wife shall have a son” (verse 10), Sarah overheard it and it was her turn to be skeptical. The narrative moves on to recount God’s intention to destroy Sodom and Gomorrah, as well as the actual destruction of the two wicked cities (Genesis 19). In the process Abraham learned how to intercede before God (for Lot and his family, as they were living in Sodom). This prepared him for what follows next in the plot.
Genesis 20 recounts the second time Abraham lied about his wife being his sister. Like the previous case, Sarah was taken by Abimelech. But unlike the previous case, God intervened before Abimelech touched Sarah. Otherwise the paternity of Isaac would be in doubt as God had promised that in less than a year's time she would bear a son. God afflicted Abimelech with a fatal disease and then said to him in a dream that he was going to die because he had taken a married woman. God had also closed the wombs of all the women in his household. Acknowledging that Abimelech was sincerely mistaken about Sarah, God told him to return her to Abraham, adding that Abraham was “a prophet, and he will pray for you, and you will live.” Abimelech obeyed. Abraham prayed to God, and God healed Abimelech and opened the women’s wombs “so they could have children again” (NIV).
Then Genesis 21 begins with, “The LORD visited Sarah as He had said, and the LORD did to Sarah as He had promised. And Sarah conceived and bore Abraham a son ....” Did Abraham and Sarah eventually believe that this was going to happen? There is no indication that they did prior to Genesis 20. This explains why God closed the wombs of the women in Abimelech’s household. For after seeing that God could open closed wombs in response to prayer (faith in God), Abraham and Sarah would surely believe that God could open her womb too. If God could open Sarah's dead womb, God could surely rejuvenate Abraham. Genesis 20 is the narrator's way of saying that Abraham and Sarah eventually believed.
Now we are ready to return to Genesis 22. We only need to add that Abraham obeyed God promptly, as he began the journey “early in the morning.” And he believed in God firmly that He would keep His word that Isaac would be his heir. For we read that when Abraham left his servants for the place where he would sacrifice his son, he said to them, “Stay here … while I and the boy will go over there, and we will worship and (we will) return to you” (verse 5). Where did Abraham learn this kind of faith?
The answer is obviously found in Genesis 12-21. We saw that his faith in God concerning an heir had been increasing step by step. When Abraham finally believed in God that Sarah would bear him a son, he “contemplated his own body, now as good as dead ... and the deadness of Sarah's womb” (Romans 4:19). He had thus come a long way, from a polytheistic background, to complete faith in the Creator God who “gives life to the dead and calls into being that which does not exist” (Romans 4:17). He obviously developed this level of faith from his experience in Genesis 20. When this faith had become sight in Genesis 21, it was just a small step forward to believe that God could literally raise Isaac from the dead.
We now consider the apparent contradiction that though God unilaterally and unconditionally guaranteed that He would fulfill the Abrahamic Covenant (Genesis 15), yet He later said to Abraham: “I am God Almighty; walk before Me, and be blameless. Then I will establish My covenant between Me and you, and I will multiply you exceedingly” (Genesis 17:1-2). In other words, Abraham had to be obedient to God for the terms of the covenant to be realized (see 22:15-18; 26:3-5; but cf. 28:13-14).
There is really no contradiction. What it means is that in Genesis 15 God Himself alone guaranteed that Abraham would truly fear and obey Him, which Abraham demonstrated convincingly through passing the ultimate test in Genesis 22. It is like a driving instructor, who is so confident that he could teach a student with poor motor skills to pass the driving test in his first attempt, that he unilaterally and unconditionally gave the student a money-back guarantee. Like what God did with Abraham in Genesis 17:1-2, the instructor would still warn the student to drive properly even before the test. Of course no human instructor can be that confident. But we are talking about the divine Instructor here. In this case, God was confident that He could work in the life of Abraham such that Abraham's faith would mature to the point where he would completely trust in the God to whom nothing is impossible, as He created everything out of nothing.
Abraham's obedience in Genesis 22 is due not just to the maturity, but also the quality, of his faith. According to Genesis 15:6 Abraham's faith was reckoned to him as righteousness, that is, counted as obedience to God (cf. Wenham 1987: 329-30; Hamilton 1990: 423-27). What kind of faith is this? Note that the verse says that Abraham believed in God, and not just in the promise of God. It is possible to believe in a promise of God, in the sense that we believe that it will come true, but not believe (trust) in God Himself. When we believe in God, we will believe in everything He says. Hence faith in God will manifest itself as obedience to Him in everything. This kind of faith is as good as righteousness. This explains why God could pre-guarantee the fulfillment of the Abrahamic Covenant in Genesis 15, ahead of its final confirmation in Genesis 22. As in the case of Abraham, faith reckoned as righteousness still needs to mature to its fullest potential.
This understanding of Abraham's faith helps us to also resolve an apparent contradiction in the New Testament. Both Paul and James consider the faith of Christians as the same as that of Abraham. Paul argues that a Christian is justified (reckoned as righteous) by faith alone, and not by works (Romans 4:1-8). But James argues that a Christian is not justified by faith alone but by works also (James 2:14-26). Interestingly, both cite Genesis 15:6 in their respective arguments.
Paul was looking at Genesis 15:6 in and by itself. He is correct that Abraham was reckoned as righteous because of his faith (in God) alone. So it is the same for the Christian. Paul is opposing those who say works (obedience) is needed in addition to faith before one is justified. James himself makes it clear that he was looking at Genesis 15:6 in light of Genesis 22 (see James 2:21), where Abraham's faith was tested and confirmed to be a living faith through his obedience (works). We have seen that true faith in God will manifest in obedience. Otherwise it is questionable whether one has faith (in God) at all. James is questioning those who say they have “faith” but have no works to back it up.