How could the Lord’s Spirit come on Jephthah and yet he kill his daughter?
We have no guarantee that – when the Spirit comes upon Jephthah at the beginning of Judges 11:29 enabling him to march across the Israelite region (gathering troops) and to face the Ammonites in their land – that when this happens everything that follows in according to the Spirit.
What if Jephthah’s own self-obsession led him to vow a vow that began thinking about all who would come to greet him in his victory (“whoever comes out”), but that by the time he reached the end it became focused on a sacrifice as a gift to God for his victory? This carelessly-made vow then had to be fulfilled when the only one who came out to greet the returning victor, rather than the crowds he expected, was his young daughter.
Even there the focus is not on her doom but on his own loss (you have brought me low). Consider that Saul also made a vow where his son Jonathan became implicated. The army would not allow him to fulfill that vow and he did not, accepting the consequences of not fulfilling his vow. Jephthah had no one to restrain him and he would not restrain himself. He would sacrifice his daughter to escape divine judgment for not fulfilling his vow.
