Anything really of Jewish worship, because that was earthly. Our worship is heavenly, it's spiritual. I don't see how these things add in any way to response from the heart to God. I understand how they might help us enjoy ourselves or have an emotional effect on us, but that won't increase what's for God, because it's only natural feeling. The only thing we can offer to Him is what He has put into our hearts. In the same way, we can't offer sentimental human ideas to God, no matter how outwardly pious they might be. We can only offer Him divine impressions which have come from Himself.
I think we do need the sanction of the Word, particularly when it comes to teaching - is what we teach founded on the Scriptures? Is what we do governed by scriptural teaching? Really, introducing elements of Judiasm into Christian worship is putting carnal limits on it, it's drawing the believer back down to earth and the things on earth, when in worship we ought to be entirely removed from that. The mount of Olives represents that, the elevation above the things of the world. The Lord led the disciples up a mountain after they sang a hymn, not to the Temple.
If we aren't going to take the New Testament scripture as a whole as our guide in worship, surely we can look at the pathway of the Lord Jesus down here. As I've said before, He never played an instrument, or did anything of the Jewish form of worship. In fact He freed His disciples from the bondage of it. He broke the Sabbath, and He could, because His is Lord of the Sabbath (Mark 2:27-28). What we have to see is the contrast between Jewish bondage and Christian freedom. Legalism doesn't come into it. It's realising that we don't need any props, rituals, buildings, or officials to worship God fully and completely. If these things add nothing to the response of the heart Godward, then really, why do we bother with them? It's really only to please ourselves. While instrumental music is an innocent and wholesome pleasure in the main - and I certainly enjoy singing hymns and songs with accompaniment - it really doesn't have a place in God's house.
I'm not a member of a denomination, no.
I think you misunderstand me, if you think that's what I'm advocating. We are wonderfully free in Christ, we have liberty before God! The veil of the temple has been rent from top to bottom, we're free to go into the holiest of holies. How could we be freer! That being the case and Christ having done it all, can we really add anything to that finished work? Absolutely not. The younger son in Luke 15 had the best robe, a ring, and sandals on his feet - he was clothed in the worth of Christ! He was perfectly fitted to go into the Father's house and make merry. All we need to worship is Christ. Nothing else we could possibly bring - the finest gold the earth can offer - could add so much as an atom of worth to an offering which consists of that One.
I know I'm repeating myself here - please bear with me - but we never in the whole of scripture find literal musical instruments connected with anything other than earthly systems of worship - the Jewish and Millenial systems.
Now... I can assure you, I'm not trying to be facetious here, I'm trying to understand the basis of the ideas you're presenting. We can do anything to express devotion and worship to God? So, if I paint a picture of a landscape, then that is an expression of worship? Or if I play an instrument, that is an expression of devotion or worship? How does what I'm doing with my hands enhance or add to what's flowing from my heart? If I worship, sitting quite still and not saying anything, is that somehow inferior to doing something with my hands while I worship? I'm sure you'd agree that it wouldn't be. So, if it my activities are adding nothing to what's flowing from my heart, then what use are the activities?