God freely offers Abraham the promise of an heir who will found a great nation and the promise of land, but God can only bring these about if Abraham and Sarah trust enough. This is the second major theme of the Abraham stories: his faithfulness to God’s promise. It is summed up in Gen 15:6 “Abraham believed the Lord, who credited it to him as righteousness.” But Abraham is not a perfect person without any flaws. In chs 12 and 20 he tries to save his own life by giving up his wife Sarah and thus risking the promise of a son.
In ch.16 he is uncertain enough to take a slave girl in order to gain a son. In ch.17, he doubts the angel who tells him that Sarah will bear a child. But these are rare moments in a life that is open to God’s direction. For one thing, Abraham always worships Yahweh wherever he stops on his travels – at Bethel (ch.12), at Hebron (ch.13), at (Jeru)Salem (ch.14). He always accepts God’s command to move on, and often has face to face experiences of God (chs 15, 17, 18). In a moment of great sorrow, he obeys God and sends off his son Ishmael to a new life to prevent any threat to Isaac (ch.21).
In all things Abraham proves devoted to God’s commands. But the ultimate test comes when God seems to demand that Abraham sacrifice Isaac back to him (ch.22). This is the high point of the Abraham story, and the authors maintain a high sense of drama and artistic skill in narrating the horrifying moment. Abraham is weighed down so greatly that he cannot bear to tell Isaac the truth, and Isaac in turn is so trusting in his father that he never suspects what is happening. The boy asks naturally curious questions, and the grieving Abraham can barely answer. He preserves the privacy of the terrible last moments by sending the servants off. Just when all seems lost, God stops his hand and provides an animal to sacrifice instead.
This story often shocks modern readers. They wonder how God could ask such a thing. Perhaps the biblical authors themselves believed Abraham could never go through with the act. But they wanted to make a point for all later Israel. It was not uncommon in the ancient world for parents to sacrifice a son in times of great need or illness to try to appease the gods. The Bible gives several examples, from Jephthah in Judges 11 to Manasseh in the 7th cent. (2 Kings 21). All of these are looked upon with horror, and the story of Isaac certainly shows how Yahweh forbade any human sacrifice – he did not want human flesh but would accept animals as an offering instead, although he most wanted faith and trust.
This whole story sums up perfectly the character of Abraham as the person of faith. In Islamic traditions, he is still called khalil Allah, “the friend of God.” Even in the NT, St., Paul cites Abraham as a model of faith (Rom 4:1-25; Gal 3:6-9). Abraham becomes the example for all Christians who believe in God’s promise yet have never been part of the Jewish people. Heb 11 says Abraham believed in the promise without ever seeing it fulfilled so that Christians have
become the receivers of the promise in Christ the true Son. Such NT passages, written in controversy against a Judaism that believed all of the essentials of faith were already revealed in the Torah, tried to get beyond the law of Moses by holding that the true promise could only be fulfilled in the coming of Jesus. For the Christian, Abraham had faith without any aid of the law to guide him, and so his faith was greater than those under the law. Such opposition between Abraham and Moses would be offensive to any believing Jew and does not do justice to a full Christian understanding of the OT.
The patriarchal stories of Abraham were preserved by the Jews themselves as a true promise and prelude to the deeper covenant and promise of Mount Sinai, and can be read in no other way, certainly not as in opposition to Moses. What lies behind the NT’s strong statements against the Torah as the way of justification before God is opposition to an attitude, found in some 1st cent. Jewish teachers, that legal observance can replace a personal faith and reliance on Yahweh’s larger demands for love and obedience. But this same opposition to legalism pervades the prophets and psalms in the OT and many Pharisees in Jesus’ time. For prophet, Pharisee and Christian, the true covenant is indeed typified by Abraham himself: a personal faith and trust in God above everything else in life.