This is a classic quote from Grudem about why he prefers essentially literal translations (sometimes called word-for-word) over the so-called dynamic equivalent (sometimes called idea for idea) For more about Bible translation see my interview with the ESV Bible translators:
“I cannot teach theology or ethics from a dynamic equivalent Bible. I tried the NIV for one semester, and I gave it up after a few weeks. Time and again I would try to use a verse to make a point and find that the specific detail I was looking for, a detail of wording that I knew was there in the original Hebrew or Greek, was missing from the verse in the NIV.
“Nor can I preach from a dynamic equivalent translation. I would end up explaining in verse after verse that the words on the page are not really what the Bible says, and the whole experience would be confusing and would lead people to distrust the Bible in English . . .
“Nor would I want to memorize passages from a dynamic equivalent translation. I would be fixing in my brain verses that were partly God’s words and partly some added ideas, and I would be leaving out of my brain some words that belonged to those verses as God inspired them but were simply missing from the dynamic equivalent translation.
“But I could readily use any essentially literal translation to teach, study, preach from, and memorize.”
~ Wayne Grudem via Wayne Grudem’s Thoughts on Bible Translation « Kowalker.com.