These two excerpts from Moisés Silva illustrate some ways that Bible translation is complex:

Silva, Moisés. “Are Translators Traitors? Some Personal Reflections,” in The Challenge of Bible Translation: Communicating God’s Word to the World; Understanding the Theory, History, and Practice: Essays in Honor of Ronald F. Youngblood (ed. Glen G. Scorgie, Mark L. Strauss, and Steven M. Voth; Grand Rapids: Zondervan, 2003), 37–38 (emphasis added in paragraph 3):

During my student days, while looking over a Spanish theological journal, I happened to notice an article on a topic I knew would be of interest to one of my professors. When I brought it to his attention, he asked me whether I would be willing to translate the essay into English for him. Since Spanish is my mother tongue, he figured I’d be able to come up with a rough translation quite quickly. I thought so, too, but to my surprise, the project became a nightmare. I labored over virtually every sentence and felt burdened that at no point was I communicating in a truly satisfactory manner what I knew to be the “total” meaning of the Spanish. Possibly for the first time I sensed what factors may have motivated the old Italian complaint, Traduttore traditore—“A translator is a traitor.”

This incident was rather puzzling and troubling to me. True, I was unduly concerned over precision—my teacher needed only a general understanding of the article’s main points (and I was too afraid of writing down something that might be misleading). It was also true that at that stage in my life, although I had served as an interpreter on a few occasions, I had little experience in the translation of written literature. But my inadequacy as a translator was not the real problem. What was disturbing to me was that I found it much easier to render Greek and Hebrew into English, even though my knowledge of those languages was almost infinitely inferior to my knowledge of Spanish! In a very important sense, my understanding of the latter (simply because it was a living language learned from infancy) was far greater than the understanding that anyone can have of an ancient language no longer spoken. Yet I struggled to express in English the meaning of a Spanish sentence in a way that I did not experience when translating a biblical text (naturally, I might struggle trying to figure out what the Greek and Hebrew meant, but that’s a different question).

In truth, there is a simple solution to the mystery. The answer is twofold. First, the very fact that Spanish was a living language for me meant that I was much more conscious of its subtleties and connotations than I could be of comparable nuances in Greek and Hebrew. As a result, I was fully aware of my failure to reproduce such features in English, whereas in the case of the biblical languages, well, ignorance is bliss. [Endnote 3: My experience thus illustrates a fundamental principle of the universe: The less one knows, the quicker one can form an opinion.] True, increased practice in translation develops one’s skills in finding adequate equivalents, but it takes years of intensive work—to say nothing of the need for an inherent linguistic and literary gift—to become a truly competent translator. There is an important lesson here for the many students, and even professional scholars, who think that after two or three years of Greek they are qualified to translate the New Testament.

But I am more interested here in the second part of the answer. College and seminary courses in the biblical languages consist primarily of guiding the student in translating word-for-word. [Endnote 4: Note that in modern-language courses students are seldom asked to translate written texts into English.] If the resulting rendering violates English syntax or makes no sense at all, changes may be introduced, but as a rule these translations are stilted (sometimes barely intelligible to a layperson) and rarely express the thought of the original in the most natural way that the rich resources of the English language make available. Most of us have thus been led to believe that if we manage to represent the Greek and Hebrew words in as close a one-to-one correspondence as possible, we have succeeded in the task of translation. But who would consider successful a Spanish-to-English translation that had such renderings as “I have cold in the feet” (instead of “My feet are cold”) or “He has ten years” (instead of “He is ten years old”)—even though these sentences conform to English syntax and their meaning can be figured out?

Moisés Silva,“God, Language, and Scripture: Reading the Bible in the Light of General Linguistics,” in Foundations of Contemporary Interpretation (ed. Moisés Silva; Grand Rapids: Zondervan, 1996), 273 (formatting added for the numbering), 275:

The task of producing a good translation is exceedingly arduous. Students of the biblical languages do not always have a good appreciation of what is involved. They have learned to produce “literal” translations by consulting the lexicon and so the process seems rather straightforward. In fact, however, a successful translation requires

1. mastery of the source language—certainly a much more sophisticated knowledge than one can acquire over a period of four or five years;
2. superb interpretive skills and breadth of knowledge so as not to miss the nuances of the original; and
3. a very high aptitude for writing in the target language so as to express accurately both the cognitive and the affective elements of the message.

Even when one has all that equipment, frustration lurks at every turn. If we capture with some precision the propositional content of a statement, we may give up the emotional nuances that form part of the total meaning. If we have a stroke of genius and come up with a turn of phrase that conveys powerfully the message of the original, we may realize that our rendering blurs somewhat its cognitive detail. Not surprisingly, some rabbis used to complain: “He who translates a verse literally is a liar, and he who paraphrases is a blasphemer!” Italians are more concise: traduttore traditore, “translators are traitors.” . . .

[N]o one translation can possibly convey fully and unambiguously the meaning of the original. Different translators, and even different philosophies of translation, contribute to express various features of the original.

Related:

1. Silva, Moisés. Biblical Words and Their Meaning: An Introduction to Lexical Semantics. 2nd ed. Grand Rapids: Zondervan, 1994.
2. The Best All-Around Book on Bible Translation
3. Reproduce the Meaning
4. Translation and the Doctrine of Inspiration
5. How Not to Argue about Which Bible Translation Is Best

Update on 3/31/2017: In my latest attempt to explain how to interpret and apply the Bible (which Moisés Silva endorsed), I include a chapter on Bible translation (pp. 50–81).