The following is from chapter 6 of The Beautiful Bride of Christ: The Doctrine of the Church in the Belgic Confession — you can order it here as a paperback and here as an e-book. All proceeds go to the John Calvin Institute, the seminary of the Reformed Churches of Brazil. The book has just been updated with a new cover designed by Márcio Santana Doria.
Imagine a church where the Bible is seldom opened on Sundays. Imagine a church where there’s usually no sermon, and if there is, it’s not about the gospel, but about how to be better, or about how to do your part for salvation. Imagine a church where the congregation doesn’t sing together. Instead, if there is any singing at all, it’s done by one person or maybe by a group standing at the front of the church. Imagine a church where the order of worship in no way reflects the covenant relationship between God and his people. There’s no back and forth, no dialogue, there’s no evidence of God speaking and his people responding. Instead, it all tends to be a one way street.
That was the story of most of the medieval church before the Reformation. Sadly, it’s still the case for many Protestant churches today. It’s almost as if the Reformation never happened. German theologian Dietrich Bonhoeffer once said that American Christianity is basically Protestantism without the Reformation. Looking at American churches in the 1930s, he could barely discern any evidence at all that these churches traced their lineage back to the churches of Luther and Calvin. This was true also with regard to worship.
Let’s reflect for a moment on what the Reformation did. The Reformation was first and foremost a rediscovery of the gospel. The good news of Jesus Christ was recovered. Men began preaching that salvation comes through grace alone. They began preaching that we can only be saved from our sins through what Christ has done for us. We receive the benefits of Christ, not by doing good works, not by doing our part on this earth or in purgatory, but only through faith in Christ. Furthermore, as we put our trust in Christ alone, as we love this Good Shepherd, we, as his sheep, want to follow him alone. His Word becomes central and all important for our lives. We recognize his authority and we submit to it. He is our Lord, our master, and we will do what he says because we love him, want to thank him, and please him. Salvation by grace alone through faith alone in Christ alone necessarily leads us back to the doctrine of Scripture alone — sola Scriptura.
Sola Scriptura gets applied to our individual lives as Christians. As individual believers, God’s Word holds the ultimate authority for everything we believe and do, for doctrine and ethics. However, this principle needs to be applied to the church as well. It was in the days of the Reformation. A big part of the Reformation involved reforming the worship of the church to bring it into line with what the Bible teaches. Sola Scriptura was applied to worship. The Bible alone could determine the way in which the church would worship God. This is the Reformed principle of worship, or the regulative principle as it’s sometimes been called.
It’s found in Lord’s Day 35 of the Heidelberg Catechism. Part of what God requires in the second commandment is that we are not “to worship him in any other manner than he has commanded in his Word.” God alone can determine the manner of his worship. The connection with sola Scriptura becomes even more apparent in article 7 of the Belgic Confession. Article 7 is about the sufficiency of Scripture. The second sentence of that article says, “The whole manner of worship which God requires of us is written in it at length.” No one can add or take away from what God requires of us in worship. We aim to follow his Word only. Article 32 is in the same vein. We must not deviate from what Christ has commanded in his Word. As a consequence, we reject all human inventions and laws introduced into the worship of God which bind and compel our consciences in any way.
Colossians 2 contrasts human commands and teachings with the way of living in Christ. In the days of the apostles, there were those who tried to introduce all kinds of extra regulations into the worship of God. Paul calls this “self-imposed worship” (NIV), or “self-made religion” (ESV); others have translated that as “will-worship.” You worship the way you want to. You follow your human commands and teachings, rather than following Christ’s Word. Such an approach to worship is condemned by Scripture. Repeatedly, Scripture rebukes those who would put man-made rules and laws either in the place of or in addition to what Scripture teaches. Think of how Jesus rebukes the Jewish religious leaders in Matthew 15. He quotes Isaiah, “They worship me in vain, their teachings are but rules taught by men.” It’s true that Jesus was not speaking directly about corporate worship in that passage. He was speaking about the making of all kinds of vows and all sorts of additional rules the Jews had devised for the life of an obedient Jew. Now if he would rebuke that, what makes you think that he would be pleased with all kinds of extra rules and regulations for corporate worship? The same can be said for what we read in Colossians 2. If will-worship or self-made religion is condemned for the everyday life of a believer, what do you think would be God’s position on what we do on Sunday as we gather in his holy presence?
 Dietrich Bonhoeffer, “Protestantism without the Reformation,” in No Rusty Swords: Letters, Lectures and Notes, 1928-1936, ed. Edwin H. Robertson, trans. Edwin H. Robertson and John Bowden (London: Collins, 1965), 92-118. Cited by Michael Horton, Christless Christianity, 237-238.
 For an excellent book-length study of this, see Carlos M. N. Eire, War Against the Idols: The Reformation of Worship from Erasmus to Calvin (Cambridge: Cambridge UP, 1986).
 Wes Bredenhof, The Whole Manner of Worship: the Sufficiency of Scripture and Worship in Article 7 of the Belgic Confession (Edmonton: Still Waters Revival Books, 1997).