I have had plenty of discussions with people about praising God. The problem with a lot of people is that they don't see the wrong in praising Him with their own personal praise that God didn't command in His worship. I'm not trying to be confusing. A discussion I had once where a man told me that it wasn't wrong for him to praise God with musical instruments, there is no harm in this. He said that music with instruments makes people feel more. I replied saying that those people are feeling the wrong thing and within the New Testament God never commanded us to use musical instruments. God commanded us to praise Him in spiritual songs and hymns and make melody with our hearts. If we all are to sing, but then you have a person blowing on the horn, you mean to say He's not wrong because he is praising Him with a musical instrument and not doing what God said to do. He then went back to the Psalms about how David praised Him with harps, the clash of cymbals, etc. I said we don't live by the Old Testament anymore and me reading psalms, (correct me if wrong) I read that was how David praised God, and I didn't see anywhere when God commanded David to do that in the first place. In Amos chapter six, God loathed the excellency of Jacob and hated his palaces then delivered up the city. One of the reasons behind doing this which is in Amos 6:5 is that they chanted the sound of the viol and invent themselves instruments of music, like David. His question to me was, "Why did God let David praise Him with music and then destroy a city because they played music like David." I couldn't answer that question fully so I'm asking you this, Why did God let David play music? Why do Christians go back to Psalms in reference to playing music if the New Testament doesn't command it? Did God ever command music instruments to be played in His worship? I'm just trying to understand why Christians think they can do whatever they want as far as praising God in His worship when He says do not add or take away. I guess people think there isn't any wrong in these things from dancing, flag shows, to music. In a sense, there isn't anything wrong with the action if all in good doing, but doing it in God's worship I think is wrong because He didn't command it.
Allow me to illustrate using the concept of circumcision. In and of itself, circumcision is neither right or wrong. "Circumcision is nothing and uncircumcision is nothing, but keeping the commandments of God is what matters" (I Corinthians 7:19). What made the difference was God's commandment. Under the Old Testament, circumcision for the Israelites was not an optional practice, it was a command of God (Leviticus 12:3). It was a prerequisite for keeping other commands. For example, no one could eat the Passover meal without being circumcised (Exodus 12:48).
Yet in the New Testament, circumcision was not commanded of Christians. And the apostles strongly pointed out that attempting to impose this practice on Christians was sinful. "And I testify again to every man who becomes circumcised that he is a debtor to keep the whole law. You have become estranged from Christ, you who attempt to be justified by law; you have fallen from grace" (Galatians 5:3-4). While the practice itself was nothing, it became something when someone attempted to make it a religious practice.
It is no different with instrumental music. Musical instruments have been around for a long time (Genesis 4:21). In and of themselves they have no particular significance. However, musical instruments were commanded by God to be used in His worship. "Blow the trumpet at the time of the New Moon, at the full moon, on our solemn feast day. For this is a statute for Israel, a law of the God of Jacob" (Psalm 81:3-4; see also Leviticus 23:24; Numbers 10:10).
In your argument about Psalms, you missed a critical point. The psalms were not just some nice poems written by David, they were inspired writings of God (II Timothy 3:16-17). That is why the Hebrews writer quoted a Psalm and in one place attributed it to David (Hebrews 4:7) and in another place attributed it to the Holy Spirit (Hebrews 3:7). Thus when we read, "Praise Him with the sound of the trumpet; Praise Him with the lute and harp!" (Psalm 150:3). This wasn't an opinion piece. This was the command of God for the Israelites. It wasn't that God let David use instrumental music, God commanded Israel to use instruments in their worship of Him.
"Woe to you who are at ease in Zion, and trust in Mount Samaria, notable persons in the chief nation, to whom the house of Israel comes! Go over to Calneh and see; and from there go to Hamath the great; then go down to Gath of the Philistines. Are you better than these kingdoms? Or is their territory greater than your territory? Woe to you who put far off the day of doom, who cause the seat of violence to come near; who lie on beds of ivory, stretch out on your couches, eat lambs from the flock and calves from the midst of the stall; who sing idly to the sound of stringed instruments, and invent for yourselves musical instruments like David; who drink wine from bowls, and anoint yourselves with the best ointments, but are not grieved for the affliction of Joseph" (Amos 6:1-6).
You completely missed the point of Amos 6. God is describing people who live in idle luxury. They are so wrapped up in their own pleasures that they don't see the doom coming at them on the horizon. Isaiah has made a similar charge, "Woe to those who rise early in the morning, that they may follow intoxicating drink; who continue until night, till wine inflames them! The harp and the strings, the tambourine and flute, and wine are in their feasts; but they do not regard the work of the LORD, nor consider the operation of His hands. Therefore my people have gone into captivity, because they have no knowledge; their honorable men are famished, and their multitude dried up with thirst" (Isaiah 5:11-13). We are not talking about people worshiping God, which is how you applied it. We are talking about people who spend their time on personal entertainment. These people thought themselves to be an equal of David's musical skills, but where David used his gifts to glorify God, these people were composing songs for themselves. God destroyed them for their sins: their laziness, their lack of care for their fellow men, and their negotiations with other countries. God didn't destroy them because they used instrumental music in their worship of God.
The point that is significant to Christians is God gave no command to Christians to use instrumental music in our worship as He did to Israel. While instrumental music is insignificant in general, it becomes something entirely different when someone tries to make it a part of our religious practice. Then people are adding things to God's worship which God did not request. Who are we to tell God what He will accept? "For do I now persuade men, or God? Or do I seek to please men? For if I still pleased men, I would not be a bondservant of Christ" (Galatians 1:10).