What is the difference between swearing, or making a vow, an oath, a covenant, a promise, a declaration, and assertion, or simply letting our “yea be yea, and nay be nay”?
You will of course realize that all these terms have to do with communicating what is in our heart to another. To make a declaration or an assertion is simply to tell another what we know in our hearts. If I tell you, “I am a married man,” I am making a declaration or an assertion. On the other hand, to make a promise is simply to tell another what we are planning to do for his benefit. If I tell you, “I will give you $100,” I am making a promise to you. But what am I doing if I say to a visitor in the church, “I will give $100 to the church building fund”? I am making a promissory declaration. So promises, declaration and promissory declaration simply describe what we have said. So long as we have stated something which the listener assumes that we believe to be true, we have made a declaration or assertion. So long as we have told someone we will do something for him, it is a promise. Promises and declarations as such are simply our words. We do not need to raise three fingers like the boy scouts do to make what we say into a promise. We do not even need to say “I promise” or “I declare” to make a promise or a declaration. This, in a sense, is what our Lord and James is teaching us when they instruct us to let our yea be yea; and our nay be nay (Mt 5:37, Jas 5:12). We must always speak the truth, and what we say we will do, we must do.
However, there are occasions when it is necessary to assure others that what we are saying is true. This is when we may make use of oaths and vows. The writer of Hebrews, for example says, “For men verily swear by the greater: and an oath for confirmation is to them an end of all strife” (Heb 6:16). To swear is simply to make an oath or a vow. An oath is simply a declaration to man in which we call God to be our witness. A vow is a “promissory oath” (WCF 22.5). However, the Scripture and our Confession of faith teaches us that a vow is “not to be made to any creature, but to God alone” (WCF 22.6; cf. Ps 76:11). In that sense, a vow is a promise made to God. An oath is a declaration made to man (or men) with God as witness, whereas a vow is a promise made to God alone, optionally with men as witnesses.
What about a covenant? A covenant may be described simply as a bond of friendship involving oaths and vows pertaining to the maintenance and enjoyment of the relationship. The text of the covenant is essentially the content of the oaths and vows thereof. Thus, when we take a membership covenant, we are essentially affirming (by oath) to one another our faith, and promising (by vow) to God before the congregation of our resolve to serve Him as a fruitful and faithful member in the covenant body which He has entered us into (see PCC Bulletin, vol. 4, no. 1; dated 7 July 2002).
When we have entered into a covenant, or have made a vow, we must not break it. If we sin by breaking our promises to man, we sin the more severely when we break our vows. Thus Solomon advises us: “Better is it that thou shouldest not vow, than that thou shouldest vow and not pay” (Ecc 5:5). Yet, the use of vows and covenant is clearly pleasing to God when they are used with a humble attitude of reliance upon Him for His help to fulfil what we have promised (e.g. Neh 10). Therefore, let us continue to use them prayerfully, but only after careful consideration of whether we truly intend to keep what we promised even if keeping it may result in pain and inconveniences on our part. Wretched is the man who makes a vow and then tries to squirm his way out of it when he finds that he no longer wishes to keep it because of some changes in the circumstances surrounding his life. Ω