This is something I think can be especially difficult among the churches of Christ just because of our tradition.
There is a very popular way of reading the Bible in the churches of Christ that goes way back to our roots and the reasoning is that a belief or practice can only be authorized if it is explicitly laid out by command or approved example or necessarily part and parcel with something that meets a command or approved example. We don't hold to that standard nearly as strictly today as way back then but it can still create this subconscious need for proof-texts whether they be valid or not.
In regards to "Careful What You Say," Romans 3 specifically involved religious curses the Greek word (g0685) more properly means prayer and by implication a prayer for destruction -- a curse. The same principle applies to the Mark 7 and Ecclesiastes 10 passages. Taken in this sense, it is also categorically false that "Jesus never cursed," as that is exactly what he did to the fig tree.
The author also misuses the example of Peter invoking a curse. First, he claims that what gave Peter away was that "he wasn't using curse words like those around him." I'm not sure how he got this, but in context, it seems more likely that that passage was referring to Peter's accent. The curses invoked were more to illustrate the massive shift from when he had sworn to sooner die than deny.
I'd also point out that the apostle Paul was effectively using euphemistic language when he compared our works to "filthy rags," and that language was further euphemized upon translation into English.
I see from your reference to G0685 that you are using the dictionary at the back of Strong's Concordance. Strong's was never designed to be a thorough lexicon for the Greek or Hebrew languages. It is, by design, brief and leaves out a lot of information. The Greek word ara, when used as a noun, refers to a vow, oath, or curse on another. In other words, it can be used positively or negatively, depending on the context. It only appears in Romans 3:14 in the New Testament. In referring to Psalms 10:7, "a 'mouth full of curses' is another expression of the hatefulness of the wicked toward others" [The Complete Biblical Library]. The Hebrew word in Psalms 10:7 is 'alah. It means to swear an oath, to denounce with a curse. Thus, like the Greek word it was translated into, it can have a positive or negative meaning based on the context. Thus, we look at the context, "His mouth is full of curses and deceit and oppression; under his tongue is mischief and wickedness" (Psalms 10:7). The context shows quite clearly that we are not talking about religious people making prayers for the destruction of their enemies. This is on the order of people who get mad and in their words ask (command?) God to condemn another to eternal damnation. This sort of speech is wrong because it places the speaker in the position of deity. When people do this, they take a serious subject and treat it lightly and with contempt.
"For Moses said, 'Honor your father and your mother'; and, 'He who speaks evil of father or mother, is to be put to death'" (Mark 7:10).
"Speaks evil" or "curses", depending on the translation, is the rendering of the Greek word kakologeo. This word means to curse, speak evil of, revile, or insult. "In this teaching Jesus did not refer to one's 'placing a curse' but rather 'speaking evil of' ('cursing') his mother or father" [The Complete Biblical Library]. It is used in a similar sense in Acts 19:9, "But when some were becoming hardened and disobedient, speaking evil of the Way before the people, he withdrew from them and took away the disciples, reasoning daily in the school of Tyrannus." This does match the definition that I gave, "Cursing is making light of something, bringing it into contempt, or giving it no respect."
"Furthermore, in your bedchamber do not curse a king, and in your sleeping rooms do not curse a rich man, for a bird of the heavens will carry the sound and the winged creature will make the matter known" (Ecclesiastes 10:20).
The Hebrew word qalal means to be small or to be light. In the Piel form, as it is in Ecclesiastes 10:20, it means to curse or express great loathing for someone. You are belittling the person and making light of his reputation. This is what Shimei did to David when he was fleeing Absalom. "When King David came to Bahurim, behold, there came out from there a man of the family of the house of Saul whose name was Shimei, the son of Gera; he came out cursing continually as he came. He threw stones at David and at all the servants of King David; and all the people and all the mighty men were at his right hand and at his left. Thus Shimei said when he cursed, 'Get out, get out, you man of bloodshed, and worthless fellow! The LORD has returned upon you all the bloodshed of the house of Saul, in whose place you have reigned; and the LORD has given the kingdom into the hand of your son Absalom. And behold, you are taken in your own evil, for you are a man of bloodshed!'" (II Samuel 16:5-8). Shimei showed no respect for his king. He treated David with contempt.
Thus, the texts do support the point that I made. Perhaps the problem is that you don't realize that "cursing" in English carries two definitions:
- invoke or use a curse against.
- utter offensive words in anger or annoyance.
I've been using it in the latter sense, but you seem to be stuck thinking that it only means the former. This is what I meant when I said that Jesus never cursed. I see how you became confused, so I'll revisit the article and make the point clearer.
Looking at the example of Peter in Matthew 26:73-74, I must agree with you that this is not an example of Peter using profanity. In fact, it is the use of "curse" in the first sense of the English definition. Peter was calling down condemnation on himself (devoting himself to destruction) and swearing oaths that he did not know Jesus. I'll change the article. Thank you for pointing it out.
There is nothing wrong with using euphemisms. It is perfectly fine to refer to a garbage man as a sanitation engineer. There is nothing wrong with using milder terms, especially in an audience that may take offense at more blatant terms. My point is that you haven't changed topics when you use a euphemism. Thus, using a euphemistic form of God's name, a curse, or profanity hasn't changed the meaning of what you have said.
Before I end this response, I would like to point out that you attempted to address the points by basically dismissing the need to find authority for the things that we do as Christians. You instead suggest that we can replace objective proof with subjective standards, such as what society accepts. See The Basics of Communication: Tell, Show, Imply, and On Some Nebulous “CoC” Thing. "Whatever you do in word or deed, do all in the name of the Lord Jesus, giving thanks through Him to God the Father" (Colossians 3:17).