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 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.