Exodus 20:7 reads:
“You shall not take the name of the LORD your God in vain, for the LORD will not hold him guiltless who takes his name in vain.”
According to our current thinking on this passage, this means I am not to utter curse words that incorporate the use of God’s name. Is this what it originally meant? I do not think so.
It seems better to understand this passage as prohibiting the use of God’s name in a deceptive promise or using God’s name to justify an act even when God has not sanctioned the act. To “take the name” of God is to speak it, as in an oath. And “in vanity” means in emptiness, or for a worthless cause. Leviticus 19:12 seems to make this clear when it rewords this command as: “You shall not swear by my name falsely, and so profane the name of your God: I am the LORD.” Again, “swear” in this verse refers to the act of making a promise, it is not addressing “swear words” as we currently understand swear words.
The primary meaning of this command is to not enter into an oath or promise that invokes the authority of God unless one is serious about fulfilling the promise. It also is a warning to those who promise to speak the truth using God’s name as a pledge and then lie (what we refer to as perjury).
So this is a verse that addresses fulfillment of promises made in God’s name or intentional dishonesty using God’s name. It is not about curse words. If you want a verse that tells us to not use foul language, look at Ephesians 4:29 and Ephesians 5:4 instead.