Flip through most Bibles, and you’ll see that some words are printed in bright red. Appearing exclusively in the New Testament, these bright red words are the words spoken by Jesus. Anytime Jesus speaks in the Bible, many Bibles will highlight all of his words in red ink.
Though red-letter Bibles are common, they’re potentially problematic. The translator’s preface to my NIV Bible says that “the issuing of ‘red-letter’ editions is a publisher’s choice—one the [translation] committee does not endorse.” That is, the men and women who translated the Bible wish that the printers would not print Jesus’s words in red. They’d prefer for the publishers to print everything in plain, black ink. The reason for this aversion to red-letter Bibles is that red-letter Bibles can become problematic if we aren’t careful.
The reason that red-letter Bibles could be problematic is that they could be taken to imply that Jesus’s words are more important than the rest of the Bible. Since they’re highlighted in red, some people might think that these words are in a class of their own. The result would be that there would be a more-inspired, more-authoritative section of scripture which publishers have conveniently highlighted in red. This would become something like a canon within the canon of scripture, more authoritative words among the authoritative words of the Bible.
Conservative Christians will recoil at this suggestion. The reason is that we believe in plenary inspiration. Plenary inspiration means that the entire Bible is inspired scripture, not parts of it. One part is not more important than another part; instead, God inspired every part of scripture. Consequently, every part must be obeyed. Thus, Jesus’s words in the gospel of John are inspired, authoritative scripture; however, so are the words of the apostle Paul in the book of Romans, David’s in the Psalms, and Peter’s in 2 Peter.
Red-letter Bibles aren’t inherently wrong so long as we remember that the entire Bible is God’s word to us, regardless of the color of the ink. Jesus’s words as the God-man are certainly important and are binding in a way that the apostle Paul’s words wouldn’t have been. However, since God inspired all of scripture, everything within the Bible is binding on us.