Language works at (at least) four levels: grammar, syntax, speech-acts, and rhetoric.
Language is an objective reality that people have described through abstracting general use. One of the earliest theorists of language Dionysius Thrax (2nd ce. BC) sketched out a theory of grammar and syntax on the basis of assumed and stated rules of language. Like Isaac Newton's discovery of the law of gravity became an assumed and unquestioned reality, so also laws of language have come to be understood—at least when it comes to grammar and syntax. Most will also affirm the reality of rhetoric—that the shape and form of speech matters for communication and that patterns of speech exists across cultures and can be discerned.
Yet fewer people are aware of speech-acts since the language to describe speech-acts is relatively new.
Speech-acts
The word speech-act falls into the same category as the word grammar. Both describe objective realities within human communications. Grammar describes the minute details of speech, whether a word is a noun or verb and so on. Speech-acts work at a higher level and define: what communication is, does, and intends.
Here are three major categories of speech acts:
A locution is the sound and meaning of an utterance.
An illocution is what a word does: so, for example, a promise binds you to something while an assertation makes a propositional claim (the world is round).
A perlocution is the intended response of an utterance. If I tell my wife she is beautiful, I hope she feels loved and will return love in kind.*
These three categories simply identify common elements of communication. Of course, people have always communicated with speech-acts but did use these words to define what they were doing.
But can we honestly say that a locution, the sum total of a sound of its meaning of an utterance, has failed to be understood in history? Of course not. But twentieth-century thinkers wanted to clarify the reality of language by using these terms.
Is this helpful?
Maybe. Theologically, we must confess that words "say" (locute) and "do" (illocute) because of the nature of God who speaks and creates (e.g., in Gen 1:3). The words of God share in the creative Word of God (John 1:1–3). Hence, we know that words both say and do things. To deny this would be to misunderstand the nature of God.
We also know that words have intent (perlocute). I can say, "You drive dangerously and recklessly, how did even you get a license?" to cut someone down even if I am accurate. Or, I can say: "I noticed that you don't signal on left turns. I am worried about your safety. Would you mind turning on your blinker" to communicate that I care and want someone to be safe.
To my mind, knowing about speech-acts is like knowing about grammar or syntax. It can be quite helpful. But it is not necessary to know.
Are we conforming ourselves to the world by using language like speech-acts?
No. The Bible itself encourages us to study the natural world to learn from it. For example, Proverbs 6:6 says, "Go to the ant, sluggard; consider her ways, and be wise." The wisdom literature of Scripture, as a whole, confirms the reality of natural law—that we can observe true things in nature. Paul himself employs an argument from natural law when he says, "Does not nature itself teach you that if a man wears long hair it is a disgrace for him" (1 Cor 11:14).
Grammar, syntax, rhetoric, and speech-acts are simply observable phenomena in nature. I grant that we need to invent the theoretical language to describe what words do. Koine Greek, for example, is notorious in having a large range of possible meanings for the genitive case. Grammarians categorize what the genitive case can do for the sake of clarity. Speech-acts are the same kind of thing, although they run at a higher level of analysis.
Besides which, Christians ought to understand speech-acts implicitly because Paul tells Christians to speak the truth in love (Eph 4:15). The point here is that our words do more than state brute facts. We can speak truth to crush or hurt others; or can we can speak truth to build up and encourage others. The latter means speaking the truth in love, the former means doing so with malice.
Speaking the truth in malice certainly won't do. It's not only about what we say but how we say it. And this is what Paul commands in Ephesians 4:15.
I have relied on and simplified Paul Maxwell's explanation of speech-acts. I encourage everyone to read his post to see a more precise and academically acceptable explanation of speech-act theory.