This is probably the most difficult portion to deal with in the entire book of Judges.

Although the text here is unclear, Scripture clearly forbids human sacrifice. Passages in Leviticus and Deuteronomy are examples. These practices were completely contrary to the mind of God for his people.

What we've learnt about Jephthah is that he had a great knowledge of the Scriptures and is one of the great men of faith in Hebrews 11, so he surely knew about this prohibition. The Spirit of the Lord came on Jephthah right before his vow, so we would expect him to not make a rash vow while the Spirit was guiding him.

Vows are a serious matter. Scripture gives guidance and makes provisions for properly handling vows. Our culture does not take vows seriously, not even the solemn wedding vows which are routinely broken, but we must take vows seriously. The Lord must be very grieved when his children make and break this vow.

Why do people even make vows?

From Jephthah's daughter we learn what a good father he must have been. She shows such deep love and respect for her father, and is not only willing to obey him no matter how difficult, but his own integrity is as important has her own in that she supports the keeping of his vow.

Was his daughter killed as a sacrifice, or was there some other explanation that fits the literal text (without adding or subtracting)? Looking carefully at what the words say happened, we are told of her virginity but not her death. Many places in Scripture tell us of women devoted to temple service, who were likely older widows. Jephthah's daughter was young. Fulfilling her father's vow deprived Jephthah of his only child and any hope of grandchildren.

Then we see the men of Ephraim again upset because they were not in the spotlight. Jephthah responds by exposing their deception, but then sadly focuses on what he had done rather than negotiating in humility as Gideon had done. How do we react when challenged by cruel people?