In Reformed/Presbyterian confessionalism, the regulative principle of worship (RPW) is right there in the fiber of the discussions on worship (HC Q/A 96, WLC Q/A 108-9, etc).
William Ames (d. 1633) defines it this way: “God must be worshipped only for the reason and by the means by which he has personally prescribed that he is to be worshipped in his Word.”
In the second commandment, he says, “it is taught…that under the names of images, every will-worship introduced by people is condemned, so that no one may approve anything other than what God personally has prescribed. Also it appears to hint at this doctrine in the phrase, ‘You shall not make for yourself’ – that is, by your own decision (arbitrio) – and you will introduce no worship by your own pleasure.”
Ames goes on and gives reasons:
1) God alone knows what is pleasing and suitable to his nature.
2) The blessing and fruit of all our worship that we owe to God depends on God himself. It is also not for us to prescribe to God the means by which it might be performed and he might be blessed by us.
3) The worship that has not been prescribed does not have in itself the rationale of obedience. Moreover, God wishes what pertains to his honor, so that by obeying we may worship him and by worshipping him we may obey him.
4) Such is the vanity and futility of the human imaginations in divine things, that if it were left to us to choose for ourselves the means of divine worship, that our entire worship would be converted into ridiculous and inane observances, just as experience teaches that the devil has in this way led humans to inane superstitions throughout almost the whole world.”
Outstanding. Don’t just skim that, read it well! It is packed with theological rationale for the RPW. On the same topic, I’m finally reading through Give Praise to God: A Vision for Reforming Worship – a sort of festschrift for J. M. Boice – which has several chapters about the RPW. I’ll post those later…stay tuned.
Quotes above taken from Ames’ A Sketch of the Christian’s Catechism trans. Todd Rester (Grand Rapids: Reformation Heritage Books, 2008), 161-2. NOTE: right now, you can get this book and Ames’ Marrow of Theology from RHB for a total of $40!