How does the vow narrative compare to the sacrifice of Isaac?

Without question the Jephthah narrative recalls the Akedah in Genesis 22:1–19. This has been duly noted in the scholarship. For starters, Römer cites some of the significant correspondences as follows:

In both cases the offering is a עוֹלָה (Genesis 22:2; Judges 11:30) and the victim is presented as his or her father’s only (יְחִיד, Genesis 22:2; יְחִידָה, Judges 11:34) child. Parallel to Abraham calling my son (Genesis 22:7) we have Jephthah’s exclamation my daughter (Judges 11:35).... Both stories have an outcome related to the issue of the offspring of the father. After an animal is substituted for Isaac, God promises to Abraham that he will have countless descendants (Genesis 22:17), whereas Jephthah’s daughter disappears without having known a man (Judges 11:39). The happy end of Genesis 22 is transformed into a tragic one. So it seems quite clear that the author of Judges 11:30–40 knows Genesis 22 and that he uses the Binding of Isaac as the background for his own construction.^1,2,3,4

The Jephthah narrative is a reenactment of the Akedah, but the import of the latter is tragically lost on Jephthah. The Lord instigates the events of Genesis 22 and is central there. He tests Abraham’s faith, and then brings him to see that what gives the Lord great pleasure is human devotion and obedience, and that human sacrifice was repugnant to him and to be substituted with an animal. Jephthah’s vow is voluntary, and issues from a total lack of faith that he could actually win without it, and then his sacrifice of his daughter only compounds the problem, leaving the reader with little surprise that the Lord is sidelined and therefore silent in this narrative.⁵ Equally if not more striking is the pacing of the narratives. The near sacrifice of Isaac is narrated in full, with the narrator exercising great care in describing the action—the building of the altar, the laying of the wood, the binding of Isaac and laying him on the altar, and the raising of the knife. We might have expected something similar in Judges 11:39, but the narrator only uses five Hebrew words, perhaps to spare the reader the gruesome details.⁶ Unlike the case of Abraham (Genesis 22:12), there is no command from God to stay the father’s knife or drown the cruel flames. Yet most fascinating of all is the proposal by James Gee that, concerning its structure, Judges 11:29–40 read forwards is in essence Genesis 22:1–19 read backwards. As follows:

Jephthah (read forward)

Judges 11:30–31
Man gives his word to God (vows)
that God will have a dead sacrifice
(= his daughter)
if (in future) God gives Man a gift
(= God allowed killing of foreigners).
But only daughter replaces animal.
Thus Man loses only child by actually
killing foreigners.
Judges 11:32–33 Jephthah does slay foreigners.
Judges 11:34 A child happens to come out;
Jephthah’s only child replaces an animal. Judges 11:35–36
Father tells child she is the offering.
Child foils father to provide the offering he has promised.
Judges 11:37–39 Daughter goes up the mountain with companions, apart from father.
Judges 11:39 Father honours vow (of the past) to
kill only child (daughter).

Abraham (read backward)

Genesis 22:16–18 God gives his word to Man (promises) that Man will have many live descendants
because (in past) Man gave God a gift (= Man is willing to kill son). But animal replaces only son.
Thus Man gains many relatives by potentially killing only child.
Genesis 22:13 Abraham starts to slay son.
Genesis 22:10 A ram happens to be there;
the animal replaces Abraham’s only child.

Genesis 22:7–8 Child asks father where the offering is. Father assures child that God will provide the offering he wishes.
Genesis 22:4 Father and son go up the mountain together, leave companions behind.
Genesis 22:2 God commands (future) father to kill only child (son).⁷

Thus, the Jephthah account is a mirror image of the Akedah account, which is a further sign that it is to be read negatively.

By the many contrasts, then, Jephthah and his affairs upset the obedience and faithfulness of Abraham. The chasm between the two men reveals how far covenant members can fall when their religion is no longer exclusively Yahwistic but now syncretistic.