regulative principle of worship
The teaching that everything done in corporate worship should be divinely warranted; that tenet that public worship should follow the directions and examples given in Scripture.

• From scripture: 
  

  And Jesus came and said to them, “All authority in heaven and on earth has been given to me. Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age.” (Matthew 28:18-20 ESV)

• From the Westminster Confession of Faith 1689:

  Chapter 21

  1… . But the acceptable way of worshipping the true God is instituted by Himself, and so limited by His own revealed will, that He may not be worshipped 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.

• From The Regulative Principle of Worship by Derek Thomas:

It is important to realize that the regulative principle as applied to public worship frees the church from acts of impropriety and idiocy — we are not free, for example, to advertise that performing clowns will mime the Bible lesson at next week’s Sunday service. Yet it does not commit the church to a “cookie-cutter,” liturgical sameness. Within an adherence to the principle there is enormous room for variation—in matters that Scripture has not specifically addressed (adiaphora). Thus, the regulative principle as such may not be invoked to determine whether contemporary or traditional songs are employed, whether three verses or three chapters of Scripture are read, whether one long prayer or several short prayers are made, or whether a single cup or individual cups with real wine or grape juice are utilized at the Lord’s Supper. To all of these issues, the principle “all things should be done decently and in order” (1 Cor. 14:40) must be applied. However, if someone suggests dancing or drama is a valid aspect of public worship, the question must be asked — where is the biblical justification for it?… The fact that both may be (to employ the colloquialism) “neat” is debatable and beside the point; there’s no shred of biblical evidence, let alone mandate, for either. …

What is sometimes forgotten in these discussions is the important role of conscience. Without the regulative principle, we are at the mercy of “worship leaders” and bullying pastors who charge noncompliant worshipers with displeasing God unless they participate according to a certain pattern and manner. To the victims of such bullies, the sweetest sentences ever penned by men are, “God alone is Lord of the conscience, and hath left it free from the doctrines and commandments of men, which are, in anything, contrary to His Word, or beside it, in matters of faith or worship. So that to believe such doctrines, or to obey such commands out of conscience, is to betray true liberty of conscience: and the requiring of an implicit faith, and an absolute and blind obedience, is to destroy liberty of conscience, and reason also” (WCF 20:2). To obey when it is a matter of God’s express prescription is true liberty; anything else is bondage and legalism.