The questions we must first ask in relation to our question:
How much of the bible is reliable?
Do the inherencies or translations in the bible change major ideas?
How do we know we have the right books in the bible?
Because the bible was written many thousands of years ago, a valid question about its reliability arises: how much of the bible is truly reliable, and how faithful is it to the original text?
The Bible is 99.5% accurate to the original text in its current translations. This does not mean that every word has been literally translated; it refers to the accuracy of the meaning toward the original word.
An example of this is the use of the word "unicorn" in the King James translation, where the word simply meant an animal with a single horn. Modern scholars acknowledge that this was most likely in reference to a wild ox, oryx, or even a rhinoceros, not a supernatural being.
Of the 0.5% that does contain differences, we see that the discrepancies do not concern any doctrinal teachings or commands. Nonetheless, the meaning of the 0.5% has frequently been determined with a high degree of certainty by reading the verse in context and using textual criticism. Not only that, but many of the modern translations often contain footnotes stating the major differences, if there ever were any.
The idea that the Bible has been corrupted is also a difficult one to prove, due solely to the sheer number of manuscripts present, unparalleled in ancient literature.
Of the New Testament, we see more than 5000 Greek manuscripts, 8000 Latin manuscripts and an additional 1000 in other languages
To put this in perspective, Greek and Latin writings, such as the esteemed works of Plato or Aristotle, only have a range of one to twenty existing manuscript copies. The discovery of the Dead Sea Scrolls in 1947 also reaffirmed the idea that the bible had been preserved well, as it predated the earliest (Masoretic) Old Testament by about 1000 years, yet had very few differences—most of the variations between the text were simply style or spelling.
Another point of contention is the matter of the "forgotten" books. Books such as the "Gospel of Thomas" have been shunned by the church, not out of a desire to hide embarrassing or contradictory text but because the book is both chronologically and culturally distant from Jesus. The book does shed light on the debates about Jesus and the nature of Christianity in the time of the Antonine emperors (AD 138–192), but the lack of historical information regarding Jesus does not permit it to be the Bible. Other books excluded are shunned for their dishonesty or clear historical errors.
Conclusion
The Bible is best understood as a discerned book containing a canon that emerged as a result of a historical process guided by God. The accuracy of the original meaning has been scrutinised, yet the evidence for the legitimacy of the translations seems to indicate that the unprecedented number of manuscripts and copies managed to retain the words that God wanted us to know.