I pastor a small church in a rural community, surrounded by Roman Catholic "churches" and mostly mainline, liberal Protestant ones. Most of them, as expected, engage in celebrating the Advent season, to one degree or another.
I've been here for four-plus years now and for the first couple of years had to explain why I, as a full subscription elder, was convinced from Scripture that the use of Advent candles, or anything of that nature, was forbidden from Scripture via the Regulative Principle of Worship.
From time to time I still get pushback on this, even from one of my elders. The line of argumentation goes like this. I tried to be as kind and pastoral during these talks with folks, even if the exact wording wasn't exactly like what follows:
Advent Proponent: "Why don't we use Advent candles on Sundays before Christmas?"
Me: "Because we confess that the Lord alone commands the proper worship of Himself and He has not commanded such things from the Scriptures. To not command something is to forbid it."
Advent Proponent: "But XXX PCA Church does it. In fact, most PCA churches do something like this? Why are you being divisive in your views when they are obviously in the minority?"
Me: "Can you show me from the Scriptures, either explicitly or deduced from good and necessary consequence, where we are commanded to light candles during corporate, public worship?"
Advent Proponent: "Well, no, but the Bible doesn't say we can't do it."
Me: "OK, so what you've just done is rejected the Regulative Principle of Worship that we believe the Scriptures teach and is summarized by our Confessional Standards. What you've done is adopted the Normative Principle of Worship. But if you want to do that then you have to allow for the person who wants me to wear a propellor beanie hat during worship to have an equally valid view as your Advent candles. Because if God doesn't determine what proper worship is then man does, and I'm not sure you really want to go down that road."
Advent Proponent: "Why are you being so dogmatic about this? What can it hurt? Our tradition is to do this." (Never mind that it really isn't, after speaking with others.)
Me: "'What can it hurt?' It seems to me that this is as clear cut example of strange fire. Nadab and Abihu offered worship that was not commanded by God and they were killed for it. Now, I don't expect the Lord to strike us down if we were to do this, even though I'm not going to test that, but I will say that I am convinced from Scripture that God has forbidden this by not explicitly commanding candle-lighting during worship for any reason."
Advent Proponent: "I just don't see why we can't do this. Other churches do it. I want some sort of tradition to pass along to my children."
At this point, I usually smile and say, "But you have that tradition available to you. It's a tradition, to use your word, of consistent attendance of the gathering of the saints every Lord's Day for worship that is established and commanded by God."
But that's not enough for some people. And sadly, the PCA has, by its adoption of good faith subscription, fed the urge for man-made traditions. Further, it's actually undercut its elders who confess fully the Westminster Standards, given them less of a practical leg to stand on because the argument is usually "well, other PCA churches do it and you can't bind them to your view of the Standards," and turned the tables to make the full subscription elder the problem and not the practical rejection of the Westminster Standards.
Most of my congregation understand where I'm coming from and have accepted the argumentation regarding this. A couple of folks, however, who feel strongly enough to try to wear me down on the subject, and as discouraging as that can be, I understand where they're coming from and why the seek to do it. That makes it a bit easier to be more pastoral and less tense about our conversations.