...There ya have it. Not using musical instruments isn't wrong and still brings glory to God. If you must have musical instruments in your worship then maybe the c of c isn't a place for you or others. But allow us some courtesy
I don't think anyone meant to say it was "wrong" to not use instruments if that is the choice and preference of everyone involved. And I don't see anyone saying that they "must" have musical instruments to worship. Certainly not I! I only see some people saying that they like to have the instruments as something that adds to their worship most of the time. As for me, I'm only saying that based on the Psalm passage that it is Biblicaly wrong to
prohibit others from using them when it is
not their choice or preference. If the CoC wants to practice this preference, that's fine for them. But please also allow some courtesy to those who do not share this preference. (And I am convinced at least for now that it is a preference.) Not using musical instruments just because there is no specific mention of them being used in the NT doesn't' make it any more wrong to use them than it does for many other things that we (even people in the CoC) do that are not specifically mentioned in the NT. While musical instruments are not specifically mentioned as being used, there is certainly not any mention of them specifically
not being used because they are prohibited that I know of.
Many times I sense a tendency of some members of such organizations as the CoC (NOT directed at anyone here) to look down on those who do things differently as being "less holy" or more worldly than they are. That's simply not right and not supported by scripture unless the thing they are being looked down on for is something that actually is prohibited (specifically or in principle) in scripture.
You said you don't agree with their line of reasoning (which I also don't agree with.) So if you were to go into a CoC church in a situation were perhaps you were a worship leader or had some other logical reason to be in the position, and you started, for example, playing a piano or an organ along with one of the worship songs... (Yeah, I know, there probably wouldn't be one there to play, but let's just use it for the question.) Would the leadership get upset and demand you stop on the basis that this was the wrong thing to do? Or would they simply allow the individual members of the congregation express their own opinions of whether they liked it or not and let you decide whether to continue or not based on what the majority of the congregation approved of? If the leaders demanded you stop because it's wrong, then this is an enforced rule against something that is not only not prohibited in the NT but is also instructed
to do in the OT. This is not allowing the congregation members to decide on their own what they prefer but is enforcing an extrabiblical rule on them. This case is where I feel it is unbiblical based on the example of scripture. IOW, to choose to sing acapela because those involved like it that way is great. (I like it too on some songs and in some circumstances.) But to say it has to be done that way with no Biblical command of this is wrong.
To me a good way to tell if it's an enforced rule or just a preference of taste is if every song in every service is acapela and people who may ask are told they may not play instruments in church because it is wrong to do so, then it is an enforced rule rather than a preference. But if it's an enforced rule in a church, it needs to be scriptural. At least that's my opinion of church rules.