The following is from Grace to You:
PHIL: Hi, I’m Phil Johnson. I’m executive director of Grace to You and I’m here with John MacArthur. And today, John, we’re going to talk about sola scriptura, what it means and why it matters. And we don’t usually use Latin on Grace to You.
JOHN: No.
PHIL: But we are today. We’re going to talk about the principle of sola scriptura. Explain to us what is that and why does it matter?
JOHN: Well that was the watershed mantra, really, of the Reformation. Let’s go back to Scripture. “Sola” means “alone.” “Scriptura” means “Scripture.” This was the cry of the Reformers, who said we go back to Scripture alone. And out of that came sola Christus, Christ alone; sola gratia; sola fide, sola Deo gloria, the Glory of God. But it all started with sola scriptura. It’s when the Reformation was born because the leaders grasped the fact that there was a single authority in terms of the spiritual world and the revelation of God, and that was Holy Scripture, as over against the Roman Catholic dual authority: the Bible on one hand and tradition and the magisterium drawn out of experiences and councils and popes, and all of that. So they were rejecting tradition as a parallel source of divine authority and coming back to Scripture alone.
PHIL: Now you said that’s the starting point. They called it the “formal principle” of the Reformation.
-Read more (listen to audio):
http://www.gty.org/resources/sermons/GTY139/sola-scriptura-what-it-means-and-why-it-matters