What are the major criticisms of the NIV? While researching for this answer and reading different posts on this site over the past few days, I've come across some criticisms of the NIV I'd never heard before. I've seen articles claiming that it changes the Bible to make it more friendly to homosexuality, but these claims were more general and more significant. For example, the one that stuck out to me the most was where someone said that the NIV translators knew no Koine Greek, just modern Greek, and that they used two secular translators to translate the NT into modern Greek. 

These are some pretty serious claims. I've never liked the NIV myself, but that’s never been anything but my personal preference. I'd link to the places I saw these claims if I could remember. What arguments exist against the NIV? I'd like to find reliable references if at all possible. I’m not looking for small, minor issues like a few missing verses. I’m looking for larger, more significant problems that could conceivably affect the integrity of the text as a whole. 

I'm not just looking for valid arguments; I'd also love to hear about any well-refuted claims against the NIV, so long as they had some intelligent basis in the first place. I know this question seems a bit open, but if any of these claims are true, I want be sure to avoid using an unreliable translation of God's words. I’m sure the same goes for others on this site and across the Internet.
I've seen three major categories of criticism for the NIV, but often people will combine two or three of them.

1. Text criticism: the NIV is based on critical texts

The NIV is a translation of the Nestle-Aland critical text of the Greek New Testament. It also critically evaluates the BHS for the OT, and often takes the Greek Septuagint as being a more reliable record than the Masoretic Hebrew.

Now most translations today are also based on these critical texts, and most people and scholars approve of their use. But there is a small minority of people who think the Textus Receptus or the Majority text is more reliable. Some of these fit into the KJV only movement, while others are not as concerned with the translation, just which source texts are used. If you see anyone talking about "missing" verses, this is what they mean: compared to the TR or MT the NIV has less verses. But most Christians wouldn't say that these verses are missing, but instead that they were added to some manuscripts after the texts were written.

2. Translation method: the NIV is a thought-for-thought translation

The NIV describes itself as "the very best combination of accuracy and readability.". It ranges between a word-for-word translation and a thought-for-thought translation. Clarity in the target language (English) is highly valued by the translators, and whole verses can be rearranged from the order which the source languages have, and which more word-for-word translations may copy. Another issue is idioms: phrases where the meaning of the whole is not found in the meanings of the individual parts. Translations like the NIV recognise more idioms than translations like the NASB, and when there are verses that are unclear in the original languages, unlike translations which translate the individual words even though they don't make sense in English, the NIV will give what the translators consider to be the most likely interpretation.

A number of people strongly disagree with any translation method other than word-for-word. In my opinion, they are misguided. Translating word-for-word is impossible to do completely, and gives little benefit even when you try.

3. Translation method: the NIV is a "progressive" translation

The NIV, and particularly its offshoot translation the TNIV (now largely merged together into the 2011 NIV), has been attacked for being progressive, in particular its gender accurate language. While some people say that it is trying to erase the gender distinctives of scripture, the changes it makes are only according to the current scholarly consensus: that the supposedly gendered language in the source languages is not actually gendered, and that formerly neutral terms in English now are strongly gendered. To ensure they were actually translating accurately into contemporary English they commissioned an independent report from Collins dictionaries to determine which words are actually used now - questions like whether it is more common to say "forefathers" or "ancestors", or "people" vs "mankind". This shows a great commitment to accuracy: true accuracy needs not only a right understanding of the source language, but also the target language. If other translations rely only on their translators' intuitions about what English is like, then we should expect they will occasionally make mistakes. This is why I don't say that it is "gender neutral", but instead "gender accurate" - the goal is not to make it neutral, but to make it accurate.



In all of these categories there are always individual verses where well-intentioned scholars will disagree. Text criticism, translation, and even knowing contemporary English are all difficult. In my opinion the NIV is a highly reliable translation for contemporary English. Even though no translation is perfect, praise God that we are blessed in English to have so many good options to compare between! And support the efforts to continue translating the Bible into every language which needs it.