Several years ago, I knew a person who made a pretty restrictive vow. I won’t go into the details, but it was a vow that bound her to a specific type of lifestyle—one that would dramatically impact her future, her potential family, and her career choices.
The kicker? She made the vow when she was fourteen.
I get why people make vows. You’re in the moment, you’re passionate about something, and so you promise to God that you will take the road less travelled in order to maintain the highest ideal of righteousness.
Martin Luther made a vow. In 1505, when he was a 21-year-old university student in training to become a lawyer, he travelled home for a visit when, according to historians, he was caught in a violent thunderstorm. In his distress, he cried out to God and vowed that he would become a monk in exchange for God’s protection in that moment.
According to everything we can read, he kept up his end of the bargain. He left university to become a monk, where he stayed for years before making every single member of the Catholic community upset by nailing a list of theses on the door of Castle Church in Wittenberg, Germany.
But did he need to fulfill his vow to become a monk? Would God hold him liable for blasphemy or lying or something else if he had returned back to the university and continued on with his studies?
The answer is no, but could also be yes, depending on when you’re asking the question.
If you could somehow travel back in time with Martin Luther to ask an Israelite in the wilderness if Mr. Luther needed to keep his vow, that Israelite would’ve almost certainly said yes.
The reason comes from Numbers 30:2: “If a man makes a vow to the Lord…he shall do according to all that proceeds out of his mouth.” Case closed.
But if you went forward to the Sermon on the Mount and had Martin Luther listen to Jesus, you could’ve reached a different conclusion. In Matthew 5:33-37, Jesus taught His disciples to “…make no oath at all, either by Heaven…or by the earth.”
That’s why this issue becomes so sticky. In the Old Testament, vows were sacred. Most of the references to vows come from the first five books of the Law—which are legalistic, by nature—and so are seen as binding. Even the story of Jepthah in Judges 11 shows the dramatic nature of vow-making-and-breaking.
Outside of Jesus’ command in Matthew 5, the New Testament doesn’t really talk about it much. Ironically, one of the only other mentions is in Acts 18:18, where it says Paul (who was a Christian at the time), cut his hair because of a vow he took.
“But wait,” you might argue. “If vows were mainly an Old Testament thing, and Jesus said not to make them, why does Paul keep one?” Good question!
Jesus’ point in Matthew 5 was not to de-emphasize vows, as much as it was to highlight the blasphemous nature of vows in the first century. People swore by heaven or by earth to do such and such a thing, as if they had any power to enforce those vows.
Think about it. If I swear by the community center down the street that I will run ten miles every day in 2026, what happens if I don’t? Will I tear down the community center? Could I tear it down? Would I even try?
The answer to all of those is no, which makes my vow pointless and stupid. That’s what Jesus wanted to put an end to.
My marriage vow that I took in 2013, on the other hand, is very much not pointless and stupid. I looked my now-wife in the eyes and told her I would lover “til death do us part,” and I meant it. If I break it, that’s on me, and God would like to have a word with me on Judgment day, thank you very much.
Getting back to our original question about Paul, he kept the vow because, even though he was a Christian, his vow was Jewish in nature. Most scholars believe this was the Nazirite vow, which is made when one wants to enter a deeper (but temporary) state of dedication to God. It’s outlined in Numbers 6, in case you want to read more.
Whether you’re referring to the Old or the New Testament, the point really was the same: When you make a vow, you need to keep it. But by the same token, when you make a promise, you need to keep it. Let your yes, be yes, and your no, be no.
Besides, if people in the world can’t trust Christians at our word, who can they trust?