In a series posted at The Decablog, Nicolas Alford (now one of the pastors at Grace Baptist Church of Taylors, SC.) explains not only the Regulative Principle of Worship, but also the Vertical and Internal Principle of Worship as well. He explains in the series introduction:
If the church at worship is the epicenter of our spiritual lives then it follows that our God would take a unique interest in what goes one there. He does. In fact, he has given us nonnegotiable Biblical principles to guide us as we think though what we do in worship and why we do it.
The three principles he talks about weave together to form and inform our worship of God. He explain in the series conclusion:
Imagine that in preparation for coming together as the church in worship, we are members of a symphony, getting ready for a concert.
The Vertical Principal of Worship has explained to us who we will be playing for. It is a concert for a King, and so while there are many others who can and should benefit from it, it is for the King. His desires and requirements must always rule.
The Regulative Principle of Worship has shown us how to build our instruments. It has shown us how to identify the parts; to indentify what is in and what is out. Using it we can build an instrument that meets the King’s design.
The Internal Principle of Worship has shown us that from within us must flow the breath that will take that beautiful instrument and make it perform the function it was designed for. The King doesn’t want us to just show him the instruments; he wants them played.
“Worship is a vertical act with horizontal impact.
We must worship God in all the ways and only the ways he has commanded in His Word.
The external act of worship must be an expression of true internal realities.”
When all the principles come together, then you have a symphony of beautiful music worthy to be offered to the King.