The New Testament commands singing for making melody and does not mention the playing of instruments for spiritual teaching, praise, and thanksgiving (Eph 5:19; Col 3:16). The instrument cannot speak, teach, or thank God with meaningful words. Christ, His apostles, and His prophets only commanded singing for worship in the New Testament. The churches in the New Testament never used musical instruments when they worshiped in song.
No believer should try to change the worship that Jesus instituted. The Bible forbids anyone adding or annulling God’s commands (Gal 3:15; Rev 22:18–19). The apostle Paul commanded, “Maintain the traditions even as I delivered them to you” (1 Cor 11:2b). Christians can no more change the fruit of the grapevine in the Lord’s Supper than change the fruit of the lips in praise to God (Matt 26:27–29; Heb 13:15). Furthermore, Jesus is sinless and His words are without error, so no one should change His commands or the words of the Holy Spirit in Scripture (John 6:63; Heb 4:15; 1 Pet 2:22; cf. John 16:12–13; 1 Cor 2:13).
Thanksgiving, praise, and edification from singing is not to entertain, amuse, or please people as the audience. Singing loses its purpose when people turn spiritual songs from worship and teaching into a show before people. Christ preached against practicing righteousness to be seen and worshiping for show (Matt 6:1–7, 16–18).
The New Testament teaches that words are essential to worship and edification in spiritual songs. Unknown languages without interpretation are excluded (1 Cor 14:7–19). Paul described musical instruments as “lifeless” or soulless comparing those using unknown languages in assembly (1 Cor 14:7). Paul expressed, “In church, I would rather speak five words with my mind in order to instruct others, than ten thousand words in a tongue” (1 Cor 14:19). The principle stands that nonverbal sounds do not fit the character of Christians singing, praying, and teaching.
Jesus established worship in spirit and truth changing worship from the physical place of Jerusalem to the spiritual place of spirit and truth (John 4:21–24). Old Testament worship was a physical worship including Levitical priests, a physical temple, animal sacrifices, and musical instruments. New Testament worship is spiritual with Christians as priests offering spiritual sacrifices in God’s temple — the church — including sacrifices of praise singing with meaningful words (John 4:21–24; Heb 13:15–16; 1 Pet 2:9). David’s worship in Jerusalem as described in the OT is not directly applicable to Jesus’s worship in spirit and truth.