Again, it has been asked:
On the discussion of instruments in the worship, can someone explain why they were never known to be used in the New Testament church until 603 AD and why they were not used in the mainline Protestant churches until 1830. Can we see that it’s an added introduction to the original church from the beginning of the New Testament church?
You'll recall that the very first church of Christ, the first generation of believers, was exclusively Jewish. These Jewish believers were surprised to learn that Gentiles/non-Jews could be saved. When they learned this ...
Acts 11:18 When they heard these things they fell silent. And they glorified God, saying, “Then to the Gentiles also God has granted repentance that leads to life.”
As Jews, they continued living and worshiping as Jews did, even to the point that Peter refused God's command to "kill and eat", not once, but three times, because that command from God himself violated Peter's Jewishness.
As Jews, the very first believers, the first Christians, praised God in the temple, in Jewish ways. The non-converts were not offended by any non-Jewish teaching, but instead held the believers in high regard.
Luke 24:52 [After Jesus ascended into heaven, the Eleven] worshiped him and returned to Jerusalem with great joy, 53 and were continually in the temple blessing God.
Acts 2:46 And day by day, attending the temple together and breaking bread in their homes, they received their food with glad and generous hearts, 47 praising God and having favor with all the people. And the Lord added to their number day by day those who were being saved.
Acts 5:12b And they were all together in Solomon's Portico [of the temple]. 13 None of the rest dared join them, but the people held them in high esteem. 14 And more than ever believers were added to the Lord, multitudes of both men and women,
Even years later, the Jewish believers remained zealous for the law of Moses and their customs, with the tacit approval of the Apostle-trained elders of this very first church of Christ:
Acts 21:20 And when [these elders] heard it, they glorified God. And they said to him, “You see, brother, how many thousands there are among the Jews of those who have believed. They are all zealous for the law, [and] walk according to our customs.
But those same elders taught the non-Jews to not observe the Jewish law of Moses (except for what was required in Lev 17-28 of "sojourners" living among Jews):
25 But as for the Gentiles who have believed, we have sent a letter with our judgment that they should [Acts 15:28 bear] no greater burden ... than these necessary things: that you abstain from things sacrificed to idols, from blood, from things strangled, and from sexual immorality...
As Jews, these first Jewish believers continued circumcising their children (Acts 21), and keeping the Sabbath and other holy days, and sacrificing animals as part of those holy day observances, and as the required ending for Nazirite vows (Acts 18:18; 21:23ff), and making offerings and undergoing temple purification rituals:
Acts 24:17 Now after some years, I came to bring gifts for the needy to my nation, and offerings; 18 amid which certain Jews from Asia found me purified in the temple,
In short, these Jewish believers kept being Jews, praising God in the temple in Jewish temple ways, which ... wait for it ... included praising God with psalms accompanied by musical instruments.
But the Jewish believers who did not live in Jerusalem did most of their assembling in the Jewish synagogue.
And guess what was missing from the synagogue.
Not because God had commanded that it not be used in the synagogue (the record reveals no commands from God about the synagogue one way or the other; the synagogue appears to have been an invention by the Jews, during their Babylonian captivity, yet Jesus approved of it, making it a custom to attend), but because it was a Jewish tradition, to remember their sadness about being taken prisoner and taken away from their temple where they had known joyous music (compare Ps 137).
And when Gentiles started being converted, where did they "learn to do church"?
In these synagogues, where instruments were not used.
So at the end of Acts, approaching the time when the temple would be destroyed, we have two branches of the Christian church: the Circumcision, taught by Cephas (Peter) and James and John, which was zealous for the Jewish way of doing things, and the Uncircumcision, taught by Paul and Barnabas (Gal 2:9), which was taught to not do things the Jewish way.
After the destruction of Jerusalem, the church grew more Gentile and less Jewish, and even forgot that the church had begun as exclusively Jewish, and started teaching more strongly against all things Jewish, including those musical instruments. The question asked above overlooks this very earliest beginning of the church, when instruments were used by the Jewish believers.
When we in the modern day teach against instruments, we do so by ignoring the New Testament testimony that the earliest church was Jewish and kept their Jewish ways, which would have included praising God with instruments, and we quote later uninspired writers to "prove" that the church had always been anti-instrument.
But if the Apostles had been teaching a new, non-Jewish anti-instrument doctrine, the noble Bereans would have demanded, "Show me the scripture!", and the Apostles would have been utterly unable to show them anti-instrument scripture, just as we can't, which is why, rather than letting the Bible be sufficient, we turn to later uninspired writings to substitute for anti-instrument scriptures, so that we may teach as doctrine a man-made command against instruments.
And that's why "we" don't see instruments used until the 600s AD., because "we" don't recognize the testimony of the New Testament of a Jewish way of worship being acceptable to God, but only recognize the later scripture-approved deviation from that way, and then the even later non-scripture-approved repudiation of that way, using later uninspired writings to support that non-scripture-approved repudiation, as if those writings are gospel.