It is true that languages that are alive evolve. Nothing we can do about it. It happens. The problem is that we don't appear to notice. That is, we often think that what one person means by a word or term today is exactly what others mean, or that it has always meant the same (evolved) definition in the past. Consider a couple of prime examples.
Recently, in doing some research, I came across a guy who claimed that the Bible does embrace homosexual relationships. "Look," he said, "at David and Jonathan." Now, my two sons, one named David and one named Jonathan, were partly named because I hoped for the very same kind of relationship for them that the biblical David and Jonathan had, so I was baffled. The author of this particular piece used, as his "proof", a reference by an earlier expositor who said that these two were "lovers". Now, there is no doubt what this guy believes the word "lovers" means because, well, it's how the word is used today without a doubt. It refers to two people who are sexually involved. (In fact, in many cases there doesn't need to be any love at all. Lots of people refer to two people as "lovers" who would more aptly be described as "lusters".) However, this is the definition according to Merriam-Webster:
1. a person in love.Today, of course, there is only one possible definition ... the last one. "Lover" today always means "two people in a sexual relationship". That's how we know that David and Jonathan in the Bible were involved in a homosexual relationship. Scripture says that Jonathan and David loved each other (1 Sam 18:1,3; 1 Sam 20:17) and early commentators referred to them as "lovers", so clearly they were involved in a sexual relationship because that is the only use of the term "lover" today. Indeed, David said his love for Jonathan was "surpassing the love of women" (2 Sam 1:26). See? It has to be! (J. Warner Wallace gives a good counter argument on his website.) (Oh, and, by the way, given David's marriages and later fall into sin with Bathsheba over sexual desire for a woman, apparently David was not "born that way" -- problematic for the "born that way" homosexual argument.) So how did we get to this divergent view? The evolution of language and the failure of moderns to recognize that the meaning has changed.
2. an affectionate or benevolent friend
3. a devotee
4. a person with whom one has sexual relations
Another example is regarding a book written in the past couple of years by a woman who argued that our relationship with God is largely sexual in nature. "What?" you may (rightly) ask. Taken to task by many Christians, she responded, "Why should that bother you? Even Jonathan Edwards wrote about having intercourse with God." There you have it! Proof! Except that she, like our misguided homosexual sex defender, failed to understand that what we generally mean by the word "intercourse" today is not what Jonathan Edwards and his contemporaries meant by the same term. As it turns out, "intercourse" means, first and foremost, "communication or dealings between individuals or groups." It may be social. It may be economic. It may be interpersonal -- an interchange of thoughts and feelings. It may be sexual (because sex is certainly "dealings between individuals"). But, while in our day it can mean nothing but a sexual relationship, in a previous, less sexually-immersed time, it did not mean that at all. Proof that Jonathan Edwards understood that a relationship with God was sexual in nature? Far from it!
These are just two examples illustrating the problem. Today we cannot speak of "love", "marriage", "gay", or many other things without it carrying widely erratic content. Worse, we cannot refer to them from prior times without it being understood in today's terms. Even worse, this problem gets assigned to God's Word. "Obviously," they might say, "when God says to love one another He is commanding us to engage in sexual relations with each other" as an example. A bad example, but not an outlandish one. It is in keeping with today's evolutionary language, where terms meant something at one point, shift in today's world, and then get shifted back then to today's modern meaning (or lack thereof).
Sometimes it is self-conscious. The King James Bible uses "charity" in 1 Cor 13 to describe something that we no longer understand the word "charity" to mean. We understand it as a voluntary giving of assistance; they understood it to mean benevolence, love, a concern for the best interest of others. So modern translations replace "charity" with "love" and we're okay (for the most part). In this case the problem arises when an older word is subverted to a new meaning and no new word can convey the older meaning. We are there now with terms like "marriage" and, apparently, "man" and "woman". More frequently, however, it is unconscious. A product of language evolution, a word takes on a new meaning and we don't even notice. We happily assign the new meaning to the old use and miss the point entirely. On the surface it is largely the result of post-modernism which claims that words mean what the reader wants them to mean and not what the author intended. And we wonder why there is such a failure to communicate. But don't be deceived. This is not a problem of post-modernism. It is a problem of sin.