This thought originates with Dr. Stephen Dray, though anything erroneous is my doodling over his brief thought at our UCCF team gathering in December. So.... there are three underlying principles in how churches do 'worship' - that is in the limited use of that word to describe the content of their church meetings.
Firstly, there's Calvin's Regulative Principle. This basically says you only do what the Bible commands. This has it's roots in the Old Testament where we see some of God's people gettting flamed for offering unauthorised sacrifices. Clearly we don't want to worship in ways God hasn't said to do, they argue.
Secondly, there's Luther's Normative Principle. This basically says you do anything unless the Bible forbids it. This is the flipside of the regulative principle. It notes that we're given very little detail about New Testament church meetings - sure the regulative principle gives us instruction to have Bible teaching, singing, fellowship, prayer and prophecy in our meetings but it doesn't tell us much about the form or the length it should take. We don't get to see many meetings in action - and even if we did, should we just immitate things. Anyone for the Six-Hour-Bible-Talk from Nehemiah? (bring it on!)
Thirdly, there's the Spirit Principle. This basically says - ask God and do what he seems to be saying. This runs around spirit-led wisdom, and we see the early church doing what they consider to be right and at times being given specific instructions by the Holy Spirit (albeit mostly in the context of mission). This principle kind of fills in the gap between what's forbidden and commanded... we know that anything the Holy Spirit says outside of scripture is subject to what the Holy Spirit says in scripture - so asking for God's help in the unrevealed gap is a reasonable idea. Some might just want to call this middle ground a place for exercising wisdom.
I was not aware of any of this underlying unspoken rules of worship until recently. It helps explain a few tense situations over the years. We're very easily shaped in our decisions by the underlying assumptions of our church, local or denominational. Mike Reeves helped me to see this in the issue of justification by faith - in the way that Catholicism is shaped by Augustine's errors, and Protestantism by Luther's Biblical correctives to Augustine's thinking. But, that is another topic all together....
Anglican's by an large are Calvinists (the Church of England, believe it or not, is basically founded on Calvin's high views of Scripture, God's sovereignty, election etc), but they depart from him in this area. The church of England is essentially normative in worship. That probably goes some way to explain the broadness of the CofE in it's practice. Baptists tend to follow Calvin's regulative principle which often leads to a much simpler and more formal approach to meetings.
One could recognise the Spirit principle misused among Quakers (where's the Bible?) or Mormon's (yes, ask for wisdom Joseph Smith, but then test what you hear...) but misuse isn't a reason to get scared. We replace misuse with right use (not non-use). Today the Spirit principle is a mark of charismatic worship in particular, and that muddiest the water because charismaticism reaches into both Anglican and Baptist circles and can easily override both previous principles (rightly, or wrongly).
Seems to me that we do need a combination of all three. Our priority should be to do what God has commanded (preaching, prayer, prophecy etc), and certainly to avoid what is forbidden. But we have to admit that God has given his church very little specific instruction about corporate gatherings. One conclusion for us is to say that 'form' is not all that important beyond the regulative/normative constraints mentioned. This gives us freedom. But it also gives us the opportunity to exercise prayerful wisdom and seek God for guidance about form.
Anything we think God is saying outside of scripture must be tested and held to losely. What seemed to be the Spirit's leading this year can quickly become enthroned in unshakeable tradition. In all worship we must let what God has definitively said, in scripture, be our overriding rule.
And, the core principle must then be the God principle. That is, our worship is less concerned with form and more with content - more with who God is. Who God has said he is, and isn't. And must be appropriate to that. Thus our worship will be marked by sorrow and repentance at our rebellion against our God, it will be marked by awe and reverance at his glorious holiness, it will be marked by shouts and singing, rejoicing and exulting over his mighty salvation.