What is a canon within the canon?

from the old testament

• The Old Testament presents its words as God’s words, even when the biblical author is the one writing. This is why the prophets regularly write in a “thus says the LORD” fashion (e.g., Exodus 20:1; Isaiah 1:2; Jeremiah 1:9).
• Likewise, even when men like Moses wrote, he expected them to be obeyed as if God had spoken directly to the people (Deuteronomy 18:18–19). Thus, the whole law was treated as binding (Deuteronomy 4:2).

from the new testament

• In the New Testament, Jesus authorized the Old Testament, teaching that three sections (Law, Prophets, and Writings) were binding (Luke 24:44) and that not even one dot or tittle (references to small strokes of a letter) would pass away, saying it was inspired down to the pen strokes (Matthew 5:18). Theologians refer to this idea as "verbal plenary inspiration," where "plenary" refers to the entire Bible.
• Paul affirmed that “All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work” (2 Timothy 3:16–17). By calling it “God-breathed” (the literal translation of “breathed out by God), he meant that all of Scripture is the very breath of God—they come with His divine stamp and authority.
• And while it is true that humans wrote it, with their personalities coming through, it is equally true that “no prophecy of Scripture comes from someone’s own interpretation. For no prophecy was ever produced by the will of man, but men spoke from God as they were carried along by the Holy Spirit” (2 Peter 1:20b–21). This means that God guided them so that it was both fully human-produced yet entirely perfect, breathed out from God.
• The New Testament, like the Old, also warns against adding to it, or removing from: “I warn everyone who hears the words of the prophecy of this book: if anyone adds to them, God will add to him the plagues described in this book, and if anyone takes away from the words of the book of this prophecy, God will take away his share in the tree of life and in the holy city, which are described in this book” (Revelation 22:18–19). While that may be referring specifically to the book of Revelation, as it’s a repeat of what was in Deuteronomy 4:2, it should be taken as a warning against removing parts in a search for the true canon.

implications for today

We must be careful about thinking of some Scripture as more authoritative than others or about ignoring some parts of Scripture entirely. All Scripture is God-breathed (2 Timothy 3:16), so all of it is equally binding and authoritative.

While there are more obvious forms of this type of misuse, even conservative Christians must be careful of this issue. One example of this is red-letter Bibles. While such Bibles that highlight Jesus’ words are not wrong to use, we must be careful not to read only the red words or to elevate them above the rest of Scripture.

Another example is when churches use creeds. While the creeds are built from Scripture, they should only remind us what Scripture teaches, not be used to define Scripture’s meaning. Yet another example is that of systems that define Scripture’s overarching theme or idea, such as Covenantalism or Dispensationalism. While helpful, such systems can also cause one to reinterpret a passage to fit a view instead of allowing the passage to speak for itself. Lastly, when we pick and choose what we read or teach instead of studying the whole counsel of God's Word, we are in danger of believing a canon within the canon.

In short, there are many ways even God-honoring Christians can fall into the trap of effectively holding a canon within a canon view of Scripture. We can guard against this tendency by carefully reading all of Scripture in its historical context and by limiting the influence of our biases so that we don't seek to make it say what we’d like it to say.