Context and Story
Despite the appearance of the minor judges, Tola and Jair, the Jephthah story picks up during the aftermath of the Gideon and Abimelek debacle. Judges 6-9 should be read as one unit, as Abimelek, Gideon's son, raised himself up after Gideon's death to avenge the bad name he thought his family received. He took a bad situation, where Israel had devolved into idolatry, and made it worse by creating an immense vacuum of leadership. Despite the forty-five years of seemingly positive leadership from Tola and Jair, Israel appears to be on a downward spiral.
There is a clear emphasis early in chapter 10 (10:6-10) on how far things have indeed fallen. An extended description of the "evil" Israel committed includes idolatry on a mass scale--Israel appears to be worshiping every god in sight except the one, true God! Thus, God, in keeping with pattern in Judges, turns them over as punishment, this time to the Ammonites. True to their part, Israel cries out to God for help, but in a change, God uses an argument originally put forth by Gideon's father (6:31). God tells them that they have turned from him even though he delivered them many times, so why don't they call on the gods they worship to deliver them!
Israel seems to get a little more serious after this. This time, they listen to God and act on their faith. They admit their sin to God, appear to be remorseful and accepting of any punishment God would send, and pack up their foreign gods and serve the one, true God. Their repentance moved God and he "could bear Israel's misery no longer." So he raised up a deliverer, Jephthah.
Jephthah's opponent is the Ammonites. He is already known as a mighty warrior (similar to Gideon, although Gideon was called one by God; 6:12) but has to be recruited by the tribal elders because he had been run out by his half-brothers over a dispute involving Jephthah's mother (she was a prostitute) and the inheritance. Jephtah is rightly skeptical when they come to him for help (11:4-11) but ultimately secures a commitment from the elders to be their leader.
Jephthah's Vow of Sacrifice
He defeats the Ammonites in a big way (11:33). But with victory comes controversy. Jephthah is empowered by the spirit of the LORD (11:29) but also makes a foolish vow designed to gain God's favor that apparently was already given to him. His vow looks noble but on closer inspection shows him to be impetuous--he promises that he will sacrifice the first thing that comes out of his house to the Lord. Presumably he expected an animal, maybe the pet dog, to come out to greet him, but instead...
...it's his daughter. And in possibly the worst irony in the entire book of Judges, Jephthah blames her for his vow! (11:34-35) Yet, of all characters in this story, and perhaps even in the entire book, Jephthah's unnamed daughter shows the greatest understanding of God. She both fears God and is faithful to him. She knows what it means to fear God and be faithful to him.
She understands that Jephthah must live up to his vow since it was made before the Lord. But does Jephthah ever consider going back on his vow? Does he ever consider appealing to God's mercy that was so prevalent in the experience of the Israelites? He acts as though his hands are tied, despite God's instruction in the law not to sacrifice children (Lev. 18:21; 20:2-5). And after an initial mourning period, he follows through on his vow and sacrifices his daughter.
There is a tradition that interprets this event as non-sacrifice but rather as dedication to celibacy. This interpretation focuses on Jephthah's daughter's emphasis on mourning her "virginity" (11:37-39). However, this interpretation, while softening the hard edge of the vow of sacrifice, does not make sense in light of the whole story. Jephthah is portrayed as irresponsible, as a gambler who, although he received the Spirit of God still needed to find security, just like Gideon did, when Gideon twice tested God after also receiving the empowerment of the Spirit (6:34-40). Jephthah was impetuous and this vow, and its consequences, highlight why he was unfit to bring spiritual change to Israel.
Was Jephthah's vow manipulative? What was the reason for it? It was already clearly stated that he had received empowerment by the Spirit of the Lord. Jephthah likely tried to manipulate God: although the Spirit was freely given, Jephthah, just like Gideon, needed to provide for himself a sense of empowerment that he could feel secure in. As a result of trusting in himself he became the very thing he sought to destroy--an idolater, a surrogate Ammonite, for whom child sacrifice was a normal part of religious experience. He focuses in himself the very experience Israel sought to rid themselves of when they cried out for a deliverer in 10:6-10.
They were so saturated with idolatry it took a great declaration from God to wake them up. But the deliverer took them right back to where they began. The similarities between Jephthah and Gideon are intentional. Things are going from bad to worse for Israel.
The Spirit of the LORD
The narrator of Judges lets us know that Jephthah was empowered by the Spirit of the LORD. This empowerment appears to have enabled Jephthah to advance boldly against the Ammonites and we're left with the impression that it was just a matter of time before Jephthah would be victorious. Yet, Jephthah disregards the Spirit's empowerment and makes a rash, foolish vow concerning sacrifice, in an effort to curry God's favor. Wasn't God's favor already with him as a result of the Spirit's empowerment?
The Spirit of the Lord in Judges is a little tricky to nail down. It works both practically in the experience of the deliverers it "comes upon" but also narratively in the story of Judges to point out the strugge and disintegration of the Israelites.
In Othniel's case (3:10-11), the presence of the Spirit meant immediate victory. But in Gideon's experience (6:34-40), he was hesitant after receiving empowerment by the Spirit; the presence of the Spirit had a delayed effectiveness. Similarly, for Jephthah, the Spirit of the Lord appeared to point him in the right direction but he stumbled, unnable to trust completely in God and it led to a devastating moment for him and Israel. Finally, by the time of Samson, when the Spirit of the Lord rests upon him, he is able to do impressive things but he is far from being a deliverer. In fact, the narrator tells us Samson only "began to deliver Israel" (13:5).
What should we make of this? On one end, Othniel was competely effective, and on the other end, Samson was completely ineffective (or just beginning to be effective). In between, Gideon delivered but reverted back to idolatry almost immediately after deliverance and Jephthah delivered but also slipped back almost immediately. His slip led the people towards violence--both in his sacrifice of his daughter and in the vicious civil war that began shortly after.
This evidence points us towards a truth about God's Spirit and how he works. As we consider the disintegration of Israel over the course of this book, we also see this represented in how the Spirit was able to work in the deliverers God raised up. When Israel was more focused in the beginning of the book, the Spirit met with great success in Othniel. As Israel began to disintegrate, become more chaotic, and take a more permanent stance against God, the Spirit began to be less effective in the deliverers.
Was this the Spirit's fault? Hardly. The Spirit was the agent of God's presence. But how can God work through a deliverer if the deliverer does not cooperate with God? The principle is this: The Spirit is effective, but not always automatically so. God's presence through the Spirit must be met with cooperation on the part of his followers. The fact that God resides within us (1 Cor. 6:19) is a mere point of interest if we are not serious and dedicated to cooperating with him in the work he desires to do in and through us.
Jephthah's story ends on a ridiculous and tragic note. Just like Gideon, Jephthah is called out by the Ephraimites, who are upset that they were not included in the fighting men. They threaten to burn down Jephthah's house retaliation! Jephthah offers an explanation, but rather than waiting to see how Ephraim would respond, he gathers a fighting force and goes against them. Ultimately, it would cost the lives of 42,000 Ephraimites.
Just like Gideon, who started so well in overcoming fear to lead a victorious army but finished poorly by taking the people back into idolatry, Jephthah began well but didn't finish well. He was rejected by his family because of his lineage but built a reputation for himself and was recruited by the tribal elders, then received empowerment by God's Spirit and led Israel victoriously through battle but left a legacy of foolishness and violence because he could not bring himself to trust fully in God.
As Jesus says, "Whoever has ears, let them hear" (Matt. 11:15).