1 Peter 1:3 – “His divine power has granted to us all things that pertain to life and godliness, through the knowledge of him who called us to his own glory and excellence.”
I know a number of catechisms and various resources, all of which teach that holy scripture gives us everything that we need pertaining to life and godliness. But if you look at the text in scripture where that teaching comes from, you see that it says nothing of the sort. Peter says that His (that is, Jesus’) divine power has given us everything we need, but he doesn’t tell us the exact mechanism.
The key difference is that the point of the text is to give you confidence that you have everything you need, and to place that confidence in the appropriate object of our faith: Jesus Christ. The point of the teaching is to narrow the means that Jesus has of giving you what you need to a specific source of information – scripture.
Now I want to affirm all the usual assertions about the authority and inerrancy of scripture. All those things are true. But we don’t bolster the authority of scripture when we go beyond the text to reach for an assertion about it’s authority. That actually undermines the text, because you are asserting something extra that you didn’t exactly get from scripture. Worse, that little extra piece doesn’t even come from some extra-biblical source that is actually recommended in scripture, such as church leaders, or a prophetic word. No, that extra bit came from that famous bugaboo of theological error, “your tradition.”