Martin Luther's recovery of the doctrine of justification by faith alone served as the theological foundation for the Protestant Reformation. He arrived at this orthodox position after a careful study of Scripture along with the conviction that Scripture alone is ultimately authoritative, not the Roman Catholic Church. Orthodoxy (right doctrine) led to orthopraxy (right practice), including the proper biblical understanding of worship. The sixteenth-century Protestant Reformation can be rightly described as a reformation of worship in the church. The Reformers, including Luther, Huldrych Zwingli, and later John Calvin, insisted that worship in the church was vital for the Christian, yet they were troubled by a number of practices in the Roman Catholic Church. This motivated them to look to Scripture, the ultimate authority, to instruct the church on how biblical worship should be practiced.
The regulative principle of worship is a term many Protestants use to describe the biblical principle for how the church should worship God. Put simply, the principle states that in corporate worship, the church is to follow the instructions of Scripture alone. In one sense, all of the Christian life is subject to a "regulative principle," because we should always be living in accordance to Scripture. There are, of course, many areas of life that are not directly addressed by Scripture; for example, What school should I attend? Who should I marry? What career should I choose? In those cases, we are to draw good and necessary consequences from Scripture to help us make wise decisions, as the Westminster Confession of Faith 1:6 teaches us. However, the regulative principle of worship goes further to explain that only those things prescribed specifically in Scripture are allowable in corporate worship. In other words, many Reformers insisted that worship is to be conducted according to the direct, specific instructions of Scripture alone.
What are the specific prescriptions for worship found in Scripture? There are five key elements. First, the Bible is to be read (1 Tim. 4:13). Second, and very significantly for the Reformers, worship must include the preaching of the Word (2 Tim. 4:2; Rom. 10:14–15). In the medieval Roman Catholic Church, preaching was diminished as the Mass was elevated in priority in worship. The Reformers insisted that preaching is central and a means of grace to strengthen believers in their sanctification. Third, prayers are to be offered in worship (Matt. 21:13; Acts 4:24–30). Fourth, the sacraments are to be rightly administered (Matt. 28:19; 1 Cor. 11: 23–26). Remember, the Reformers determined that the Bible teaches only two sacraments: baptism and the Lord's Supper. Finally, singing is also included as an element of worship (Eph. 5:19).
The element of singing in worship does give an example of some of the difference between the Reformers in their understanding of biblical worship. Luther loved music and composed a number of hymns, including the famous "A Mighty Fortress Is Our God." He believed that singing both the biblical Psalms and new hymns is an important part of worship. Moreover, Luther believed that the New Testament era gave greater latitude in worship compared to the Old Testament. John Calvin, however, had a much stricter understanding of the regulative principle as it pertained to singing in public worship. Calvin argued that only the words of Scripture should be sung in the worship service. Thus, the book of Psalms was put to metrical verse and sung in many of the Reformed churches influenced by Calvin. The legacy of Calvin's approach can be seen also in the Puritans of the seventeenth century, as found in the Directory of Public Worship produced by the Westminster Assembly.
One might fault Calvin for being so strict in his appropriation of the regulative principle, yet we must remember the context in which Calvin and other Reformers were laboring. The Reformers considered many practices within the Roman Catholic Church idolatrous. The use of icons and relics, the priority of the Mass, and prayers to the saints and Mary were all practices that turned one from worshiping the true and living God to some other person or physical object. For the Reformers, these practices were in clear violation of the teaching of Scripture. Consequently, to restore true worship and combat idolatry, Calvin and others followed and put into practice at times a stricter understanding of the regulative principle.
The recovery of biblical worship is a direct fruit of the Reformation. In many ways, the worship services of most Protestant evangelical churches today, especially with the centrality of preaching, can be traced back to the Reformation. As in the Reformation, disagreement continues today on the application of the regulative principle. Nevertheless, disagreement on this issue should motivate us to return to Scripture, our ultimate authority, to instruct us on how we should worship our God.