All Christians attribute power and authority to God’s word, for the simple fact that it is God’s word. In his Sufficient Fire talk, Phil Johnson mentioned that Brian Maclaren attempted to make milage over the fact that 2 Timothy 3:16 said that Scripture was useful, not that it was authoritative. In my later talk I chuckled a bit over that, wondering how much more authoritative you could get than “God-breathed”!
I find John Frame’s phrasing of Scripture’s authority very helpful and memorable:
[Scripture] imposes on them an obligation to respond in an appropriate way. That is the proper definition of authority: an authoritative word is one that imposes obligations on those who hear. And the word of God imposes an absolute obligation.
[John M. Frame, Systematic Theology: An Introduction to Christian Belief (Phillipsburg, NJ: P&R Publishing, 2013), 529.]
There are obvious implications to this. It’s easiest to see in the commandments. For instance, when God says not to commit adultery (Exodus 20:14; Ephesians 5:3 ), I’m to obey by not committing adultery. When God commands that we love Him (Deuteronomy 6:5; Matthew 22:37 ), we know we are to love God.