Irrelevant Vows?
According to Barry Webb (Judges) Jephthah’s vow was “an irrelevancy; he would have been victorious anyway.”
But then couldn’t you say that about any vow (at least, once you know the outcome)? Should we tell Hannah in 1 Samuel 1 that her vow (i.e., if you give me a male child, I will dedicate him to you) was irrelevant because God was going to give her a male child anyway?
In fact, couldn’t we say this about prayer of any kind (“You prayed for Bob’s healing, but your prayer was irrelevant because, as it turns out, God was going to heal Bob anyway”)? But that’s a dangerous form of unbelief. God tells us to pray and assures us that he responds to our prayers, and we aren’t allowed to think that they are irrelevant because “he was going to do it (or not) anyway.”
But if there’s nothing irrelevant about praying for Bob’s healing or for Hannah to make a vow in her prayer for a son — and there isn’t! — then there’s no basis for saying that Jephthah’s vow was irrelevant either. Jephthah prayed and God heard his prayer and granted his request.