Although it is true that the original manuscripts of the gospels and other New Testament documents were altered, expanded in some cases, spliced in some cases, and so forth by scribes as they copied new manuscripts from old ones, this hardly justifies the comment that “History has never had a definitive version of the book.”  The scholarly science of textual criticism is devoted to taking the disparate biblical manuscripts and determining which “version” of each word, phrase, and sentence in the Bible is most likely to have been the original one.  This is a huge undertaking, but the result of thousands of scholars working over several centuries is that we now have “critical” editions of the Greek New Testament (and the Hebrew Bible) in which scholars and ordinary readers can place a very high degree of confidence.  For at least 99% of the New Testament there is really not much dispute about what the original text looked like.