In Judges 11:34-36 we see that the vow Jephthah made was completely voluntary but God was not requiring a vow or any sign to fulfill his promise. It was completely unnecessary to manipulate God in doing what He already wanted to do “deliver His people though Jephthah”. He had utilized diplomacy with those who sought him out to defend the nations successfully. He had used diplomacy with the king of the Ammonites to get them to leave unsuccessfully. But friends, “You can never use diplomacy with God who knows the thoughts and intents of your heart. God doesn’t want to make a deal with you, He wants unconditional surrender!” The problem with Jephthah was not the sincerity of the vow or the zeal to carry it out. It was he fell out of touch with the nature and character of God and thought that to get what he wanted he would need to make a deal and carry it out. Folks, all we need to do to ensure God’s promises for our lives is simply believe that He is who He said He is!
I’m afraid that many have adopted a physical workout mentality to spiritually that says “No pain, no gain” but the truth of the matter is that it is “His pain that has caused us to gain”! Jephthah thought that if he committed himself to something that was extremely unpleasant he could “buy” God’s grace. God’s grace is not for sale because it’s already been lavished upon us while we were still sinners.