In the O. T. people made vows to God in an effort to obtain a special blessing or give thanks for a special blessing. These special promises were not to be made lightly, but every effort was to be made to fulfill them (Numbers 30:2). It was possible, however, to take a vow back. This mandated paying a penalty of 20% on the assessed value of whatever you devoted to God. Leviticus 27 deals with redeeming or taking back your vow. King Saul made a foolish vow to God. This vow involved executing his son, Jonathan (1 Sam 14:24-46). The people would not allow Saul to carry out his promise. It seems clear that it was not God’s will for Saul to carry out a foolish vow that he made rashly.
In the church age, we are not under the Mosaic law. If a believer makes a foolish promise to God, he does not have to pay a financial penalty for not keeping it. In my opinion, a believer who has failed to keep a promise to God, should confess that to God as a sin (1 John 1:9). The blood of Christ cleanses us from all sin-even foolish, careless promises made to the Lord. If the vow involved obligating the person to things he cannot fulfill, or things that are contrary to God’s Word, he should confess that as sin as well. We should never make promises to God lightly, for that is tantamount to taking God lightly. I do not believe that God will hold a person to a foolish promise.
The person who has made a promise to God centered in something that he or she describes as “the only thing I have to live for” needs to confess and forsake the sin of idolatry. As Paul said, “For me to live is Christ.” The primary goal of life is not a particular blessing from God, but the God who gives the blessing. Having made a foolish promise to God will probably not result in losing something dear, for God merciful forgives, but to elevate a blessing above the Lord who gives it could likely be a reason for the Lord to withhold it.