The Bible teaches that we are not to add or take away from the commands of God. Do you agree?
I agree. The difficulty lies in the application.
It astounds me that, of all the things we've discussed, only instrumental music as an accompaniment to singing amounts to a modification of God's command in your view. This is prima facie denominational bias, not based on reason at all.
You're welcome to live according to it if you like, but you must not attempt to hold all of Christendom to this standard.
I tell you the truth, your reasoning puts me in the mind of nothing so much as Matthew 23:16-22. Be careful, brother. Be very careful.