The Regulative Principle of Worship

I firmly and joyfully affirm that we are called to worship God according to His revealed will. The Westminster Confession of Faith puts it like this in 21.1:

The light of nature showeth that there is a God, who hath lordship and sovereignty over all, is good, and doth good unto all, and is therefore to be feared, loved, praised, called upon, trusted in, and served, with all the heart, and with all the soul, and with all the might. But the acceptable way of worshiping the true God is instituted by himself, and so limited by his own revealed will, that he may not be worshiped according to the imaginations and devices of men, or the suggestions of Satan, under any visible representation, or any other way not prescribed in the Holy Scripture.

In the Old Covenant worshippers were still called to worship only according to God's revealed will (see Leviticus 10) but they did so in a wide variety of ways that all pointed to Christ and have since been fulfilled in Christ. Worship in the New Covenant is meant to be simple because of the surpassing glory of the Cross. The whole world changed on the cross and so our worship changed as well. As Hebrews 1:1-2 reminds us "Long ago, at many times and in many ways, God spoke to our fathers by the prophets, but in these last days he has spoken to us by his Son, whom he appointed the heir of all things, through whom also he created the world." We have traded in the multitude of decorations, sacrifices, holy days, and rituals for the clarity and simplicity of Word, Sacrament and Prayer on the Lord's Day. God has promised to work through the ordinary means of grace and as such we should simply seek to be faithful stewards.

Over the years I found the Directory for the Publick Worship of God, the OPC's Directory for Public Worship, the PCA's Directory for Public Worship, What Happens When We Worship by Jonathan Landry Cruse and With Reverence and Awe: Returning to the Basics of Reformed Worship by Hart and Muether to be incredibly helpful and winsome resources for what this looks like in practice.