Most of us who grew up going to church have absorbed far more than we might think. We have picked up "the rules" for how and how not to apply the biblical text. Many Christians talk about the idea of the "Bible alone," but they are unaware of the degree to which they bring these rules to the Bible with them. Give a Bible to a person who knows nothing of Jesus or Christianity, send them away to read it. Apart from a miracle of the Holy Spirit, they will likely come back ready to start a cult.
Christians throughout the centuries have exercised the "spiritual common sense" we mentioned earlier. One person's prophetic sense of the Holy Spirit can turn out to be authoritative, but imagine the collective spiritual sense as it has been tried and tested for 2000 years! That doesn't mean that the collective church universal cannot ever be wrong. Those of us who are Protestants believe in particular that some of the correctives of the Protestant Reformation were right on track.
This sense of the one holy, universal, and apostlic church is found most noticeably in the common creeds of Christendom, the Apostle's Creed, the Nicene Creed, and the Athanasian Creed. These creeds ironed out things like the Trinity and the nature of Christ's divinity, the essential "dogma" of historic Christendom. But even beyond these creeds are beliefs that are commonly held by almost all who have historically called themselves Christians: belief that God created the world out of nothing, belief that we are conscious in between death and resurrection, doctrines that are the "consensus of the church."
These beliefs constitute the "rule of faith" and set boundaries for how we appropriate the biblical text. Evangelicals have tended to use their intelligence and skill to make their interpretations of Scripture come out to teach these things. However, this tendency sets up a kind of paradox in which a particular view of the biblical text--meant to elevate the value of the text--leads one not to listen to the text in deference to one's theology.
A far more honest method is to let the text mean what it meant and then acknowledge that there is a flow of revelation that moved not only from the Old to the New Testaments but also into the church as well. We have already discussed these dynamics in our section on hermeneutics.
So the "rule of faith," the consensus of the church, stands as a boundary for how we can appropriate the teaching of the Bible. We must always allow for prophets like Luther to prevent the church from the rigidity of having to justify beliefs that have been commonly held in the past but which we now can see to be phases of history or even inappropriate trajectories. For example, there was a time when it was the consensus of Christendom that ministers should not marry. This may have been appropriate for the medieval phase of Christendom, but it seems problematic today. In situations like these, the original meaning of Scripture can play a crucial role in the debate, as it did in the Protestant Reformation.
If the rule of faith provides the rules for belief, the "law of love" constitutes the rule and boundary for ethics and action. The law that a believer should do nothing that contradicts love of God and neighbor not only has the dominant hand in the New Testament, affirmed by Jesus (Matt. 22), Paul (Rom. 13), and James (2). But it has been reaffirmed by prophets of the church like Augustine.
These two "rules" form the boundaries of how we can appropriate Scripture. Our appropriations must cohere with the rule of faith, the consensus of the church as regards our beliefs. They must also cohere with the royal law of love. No appropriation of Scripture that is inconsistent with love of God or neighbor can be properly considered Christian.