The principle of the Bible being the only rule of faith and practice for a Christian is, to me, the fundamental principle of the Restoration Movement. I think all the other principles are an extension of this one. While we might not (will not) agree with how to interpret the Bible, I think it is where we can find the unity Christ’s Body (the Church) needs.
In chapter 6 of Introduction to the Restoration Ideal, Marshall Leggett summarizes the importance of the Bible. Leggett writes:
“God solved a dilemma with the Bible. He wanted to reveal those musterions hidden in His heart. Musterion is the Greek word in the New Testament often translated as ‘mystery.’ However, it does not mean a mystery in the sense of a puzzle or a riddle. Instead, it refers to that which is hidden from finite understanding, beyond the range of natural apprehension. It would be a truth man’s mind could never conceive without Divine help.” (p. 47)
In other words, without the Bible, we could never accurately know who God is. We could get some idea that God exists, but His character, love, purpose, and plan would allude us. Instead of worshipping God, the Trinity, who would worship created things: things we can see or the evil spiritual forces that we can’t see. The Bible is important, because it reveals to us, in the best terms that we can understand, who God is and how He wants us to live.
As a Christian, I can never hold on to an idea of who God is, that is not supported by His word. The Bible is what I know God has revealed about Himself, the rest is just conjecture. It is for this reason that we need to be on our guard against people who dismiss or misuse the Bible. The best way for us to be on guard against such people, Satan being the number one abuser, is to familiarize ourselves with what the Bible says. If we are students of Scripture, then we will be less likely to be led astray. If we only have a casual understanding of the Bible then we will be pulled this way and that by people who sound like they know the truth.
The follower of Christ Jesus has a responsibility to be familiar with the Bible. Only the Bible offers us the words of truth that we need to have a solid foundation for our faith in God. The Bible opens up the mystery of God so we can understand who He is and how He wants us to live.