The regulative principle teaches that in worship we aren’t just to avoid unbiblical practices; we are to avoid any practices which we’re not specifically, positively told to do by Christ. Underlying this is a conviction about the perfection of what Jesus Christ, our great high priest, is doing for us in heaven.
If you play with perfection, you spoil it.
Let’s say you’re entrusted with the Mona Lisa for a day. Do you think you could make some additions to Leonardo da Vinci’s work that will improve it?
Or imagine, you’ve been given the perfect recipe. It was developed by a top chef in a French kitchen, and won lots of awards. It cannot be bettered. But you decide to improvise, and add some new ingredients. Is it going to taste better?
The whole point of perfection is that it cannot be bettered. It cannot be improved. All that happens when you change perfection is that you ruin it. Any additions make it worse.
This is how the book of Hebrews views New Testament worship: it’s perfect. Old covenant worship was a “shadow” and a “copy” (Heb 8:5; 10:1), and “symbolic” (Heb 9:9), but it “made nothing perfect” (Heb 7:19). But Jesus Christ, as our great high priest, has been “made perfect” (Heb 5:9), “perfection has been attained” (Heb 7:11). “The Son has been made perfect for ever” (Heb 7:28).
