This subject of biblical swearing provides yet another example of the necessity of systematic study in the Scriptures. It is impossible to subject to the authority of just one text as we are reading it, because submission occurs at the point of obedience in real life. And when it comes time to swear, or not swear, what text do I go to? The one last read? We must constantly adhere to the pattern of tota et sola Scriptura -- all of Scripture and only Scripture.
"Again you have heard that it was said to those of old, ‘"You shall not swear falsely, but shall perform your oaths to the Lord.’" But I say to you, do not swear at all: neither by heaven, for it is God’s throne; nor by the earth, for it is His footstool; nor by Jerusalem, for it is the city of the great King. Nor shall you swear by your head, because you cannot make one hair white or black. But let your ‘Yes’ be ‘Yes,’ and your ‘No,’ ‘No.’ For whatever is more than these is from the evil one (Matt. 5:33-37).
Christians have real theoretical difficulty with the concept of "bad words." To get past this, we need some definitions. Many Christians simply reject the use of "bad words" and what constitutes bad words is simply determined by cultural usage. But this tends to a prudish Victorianism, and not to biblical morality. We must distinguish the two. Considering this in the light of some of our verbal distinctions (in English) might help cast light on the subject.
Cursing is calling down harm of some kind on another. There is ungodly cursing (Ps. 10:7), and godly cursing (Gal. 1:9). Vulgarity is a "crass" reference to bodily functions. There is ungodly vulgarity (Eph. 4:29, 5:4), and godly vulgarity (Is. 64:6). Obscenity is the same thing as vulgarity, only with a sexual reference. There is ungodly obscenity (Eph. 5:3), and godly obscenity (Ez. 23:20). Not surprisingly, swearing follows the same pattern, as can be seen in what follows.
What did the law require? What was Christ responding to? The content of His prohibition shows that Christ was teaching against glibness in swearing. The Old Testament did the same. But the Old Testament was distorted by the Pharisees to make it say that glib swearing was lawful, so long as a person kept his word. But Christ objected to swearing "on a stack of Bibles." His point is almost completely missed by many pietistic Christians today. Many times they have scruples about using the name of God seriously, but no problem with a swearing use of created things.
But the Bible requires solemn swearing. "‘And you shall not swear by My name falsely, nor shall you profane the name of your God: I am the LORD" (Lev. 19:12). And here is another command -- ""You shall fear the LORD your God and serve Him, and shall take oaths in His name" (Dt. 6:13).
We have New Testament examples of the same thing. Some might want to say that these commands are irrelevant because they were given in the Old Testament. But this is wrong-headed -- remember the words of Christ earlier in this chapter. He did not come to set aside the law. Furthermore, we see New Testament examples of obedience to these commands, in the area of swearing. St. Paul provides us with several examples:
"I tell the truth in Christ, I am not lying, my conscience also bearing me witness in the Holy Spirit . . ." (Rom. 9:1).
"Moreover I call God as witness against my soul, that to spare you I came no more to Corinth" (2 Cor. 1:23).
The author of Hebrews tells that there is nothing wrong with swearing.
"For men indeed swear by the greater, and an oath for confirmation is for them an end of all dispute" (Heb. 6:16). And he shows in this passage how God Himself swears: "For when God made a promise to Abraham, because He could swear by no one greater, He swore by Himself, . . . Thus God, determining to show more abundantly to the heirs of promise the immutability of His counsel, confirmed it by an oath . . . (Heb. 6:13,17).