(Matthew 15:9) But in vain they do worship me, teaching for doctrines the commandments of men.
All my life, raised in "mainstream" Texas churches of Christ, this verse has been applied against everyone but "us", because "they" don't have the truth and they "invent" doctrines. But that's really not consistent with the context of the passage.
In context, Yahshua is condemning those religious leaders who believed that all the answers were in the text of the Bible, and that it was imperative that they dig and analyze and apply their human logic to determine exactly what God meant and how the scriptures should be applied in everyday life. On the surface, this sounds like a very noble thing, but in practice, it resulted in the leaders making laws where God had not made laws. These laws eventually became known as the "Oral Law" (or "tradition of the elders", as verse 2 puts it), as opposed to the written Law from which they were derived.
It was these traditions which Yahshua condemned as vain worship.
In another place, Yahshua pointed out how that "poring over the scriptures" thinking that's how to find eternal life (John 5:39) does not result in finding that life; instead, life is found by putting your trust in Yahshua, not in the Scriptures and your own understanding of them.
We see the same principle at work in today's church. We've pored over the scriptures and dug and analyzed and applied human logic to come up with laws which we deem binding, which God never specified. For example, I suspect that some on this list would absolutely deny the validity of a church which had a sign out front that said "Church of God" instead of "Church of Christ". Did God ever specify that the sign out front should say "Church of Christ"? No, but some of us have created a tradition that is now taught as doctrine. Another example is that a faithful Christian must attend worship services each of the three times a week that the local church meets. God never specified a thrice-weekly schedule, nor that Christians are unfaithful if they skip attendance "too often". But this tradition has become, in the minds of many, a doctrine. Yahshua condemned such man-made doctrines as vain worship.
If you doubt that this is really an issue in today's church, I challenge you to pick any well-established tradition at your local church and try to change it. Confusing tradition with doctrine is a natural human tendency, and we need to be wary of it in ourselves. I suggest you make it a habit to change things up at your church and in your personal life often, just to exercise your tradition-aware muscles.