What could possibly use some attention in a sermon that includes Judges 11:29–40 is the matter of vows. Vows are fine to make still today, and those who marry, have their children baptized, take up office, etc., make vows before the Lord. Vows are given in relation to sacrificing oneself to the Lord in this or that area of life. Jephthah’s vow, however, was a paragon of selfishness. He was only interested in a bit of suffering in the event the Lord gave him victory. In addition, his vow was completely unnecessary. The Lord had given him his Spirit in order to wage holy war against the Ammonites. Jephthah took the vow of his own volition (which in itself is typical), but did not need to, and it cost him dearly. There is something in this for us as well. Jephthah used this vow as a sort of bargaining chip with God, a way of bribing him. We too can adopt the same mentality, that God accepts us, does something for us, on the basis that we have first obeyed him in some fashion. We can divorce our obedience before God and his blessing from Christ’s obedience imputed to us. We can fall into the same kind of works-righteousness thinking as the Pharisees, or the semi-Pelagianism of Catholicism.

Clearly, this episode teaches us to be careful with our words. Once said, they cannot be unsaid. We need to pray, with the psalmist, that God would set a guard over my mouth (Psalm 141:3). And it reminds us that God can write straight with crooked pencils. We must beware of mistaking God’s work through us for evidence that God has finished his work in us. Just because we are good speakers, leaders or teachers, and just because God is using us, does not mean our hearts are pleasing to him.