I’ve run across people who say a Christian should never make vows. They typically quote Jesus’ words in Matthew 5:34-37 and/or James’ words in James 5:12, texts which seem to say that no follower of Christ should ever swear an oath or make a vow. Historically, Anabaptists are against any kind of vow.
But it’s not that simple. There are many examples in the Old Testament were vows are looked upon quite favorably (e.g. Ps. 56:12). God even gives laws on keeping vows and oaths (e.g. Num. 30). The third and ninth commandments have to do with making and keeping vows properly. Furthermore, God himself is an oath-making God – he made divine promises to Abraham and David, for just two examples (c.f. Heb. 6). On top of this, Jesus answered Caiaphas affirmatively when put under oath (Mt. 26:63-64), and our Lord often used an oath-like term, truly truly (‘amen’; e.g. Mt. 5:18). Paul called God as his witness more than a few times (e.g. Rom. 1:9, Phil. 1:8). And the Angel in Revelation 10:5-7 raised his hand and swore an oath to God. So there are examples in the OT and NT of vows/oaths in the positive sense.
What then do we do with the words of Jesus and James concerning oaths? We have to remember, as Calvin said, not to make God contradict himself so that he “forbids and condemns what he once approved by enjoining it upon men’s behavior” (Institutes, II.8.26). Here’s Calvin on Jesus’ teaching:
“It was not his purpose either to slacken or tighten the law, but to bring back to a true and genuine understanding what had been quite corrupted by the scribes and Pharisees. If we understand this, we will not think that Christ condemned oaths entirely, but only those which transgress the rule of the law. (ibid.)”
Calvin does write more on this, and it is worth reading. J. Douma, echoing Calvin, also writes well on this:
“Jesus is clearly refuting both Jewish causistry and superficial swearing. People were using oaths not in a spiritual way, but a clever way. An oath invoking the name of Yahweh must be kept, but in order to escape the tightness of such a requirement, people swore, ‘by heaven,’ ‘by the earth,’ ‘by Jerusalem,’ or ‘by my head.’ When swearing by these authorities, they did not need to be so careful about the truth, or so they imagined. It was against this deceptive use of oaths that Jesus came with his redirecting Word: ‘Do not swear at all; when you say yes, let it be truly yes, and when you say no, let it be nothing else than no.'”
“So when Jesus (or James) says that we must not swear at all, we must read this emphatic statement in its context: ‘Do not swear at all, neither by heaven, nor by the earth, nor by Jerusalem, nor by hour heads. Every superficial oath is from the evil one.’ Jesus is not saying, ‘Do not swear at all, period.’ Nor is he saying, ‘Do not swear by God.’ But he is rejecting every kind of swearing that uses an oath for pulling a trick on someone.”
This is helpful, and it makes biblical and logical sense. This is why in the tradition of the Reformation, we have membership vows (public vows about following Christ), leadership vows (minister, elder, and deacon), and it’s why we approve serious, solemn vows like marriage vows and government vows (e.g. military). There’s even a chapter on lawful vows and oaths in the Westminster Confession (ch. 22). Among other things, it says that “an oath is to be taken in the plain and common sense of the words, without equivocation, or mental reservation.” In other words, lawful, wise, biblical vows are appropriate for the Christian.
In conclusion, consider God’s word from Ecclesiastes 5:4-5 (NASB):
“When you make a vow to God, do not be late in paying it; for He takes no delight in fools. It is better that you should not vow than that you should vow and not pay.”
The above quotes by J. Douma are found in his book, The Ten Commandments, p. 92-93.