The main problem with the validity of the modern versions is that they are translated from what is called an eclectic. [pick and mix] The majority text of both the old and new testament, which was traditionally accepted by bible believing Christians [the reformed protestants] for centuries has been altered in these modern eclectics. Two manuscripts from Alexandria Egypt, vaticannus and sinaiticus, which show certain evidence of corruption by gnostic heretics, are mixed in with the majority text to form the modern ecclectic texts from which most modern versions are translated. For a detailed analysis of the evidence of gnostic corruption in the vaticannus and sinaiticus manuscripts go to this website: http://www.studytoanswer.net/bibleversions/gnostic.html In the places where the traditionally accepted text disagrees with the corrupted vaticannus and sinaiticus, the words of the corrupted manuscripts are chosen and used. This causes that most of the modern versions, like rsv, nasb, niv to be different from the King James version in about 5% of important places that pertain to Christian doctrine. The ecclectic texts are a pick and mix invention of the people that produce it. They choose what words to throw out of the traditional text and what words to add from the Alexandrian text. The NIV for example as well as other versions is translated from what is called the nestle-aland eclectic; it is in its 27th edition for the niv. Those people that produce these eclectics are literally changing the Word of God according to their own choosing. This is something that the bible says you may not do and serious punishments will be on those that do it. Note this warning from the book of Revelation: Revelation 22:18 For I testify unto every man that heareth the words of the prophecy of this book, If any man shall add unto these things, God shall add unto him the plagues that are written in this book: Revelation 22:19 And if any man shall take away from the words of the book of this prophecy, God shall take away his part out of the book of life, and out of the holy city, and from the things which are written in this book.