Worship is grounded in our relation to God, as creature to the Creator. That means we must come before God on His terms. The gifts we offer are those He appoints.
Instrumental music was an act of worship and not an aid in the Old Testament. It was a separate act. Playing an instrument is doing something different from singing. To offer mechanical music would require explicit authorization from God.
When Paul was confronted with disorders in the worship assembly of the church at Corinth, he invoked the standard of what “edifies the church” to govern the conduct of the worshipers (1 Corinthians 14:4, 6, 9, 12, 19, 26). What goes on in the assembly must be intelligible, understandable. Rational, spiritual, vocal music corresponds to this criterion. “Each one has a hymn, a lesson, a revelation, a tongue, or an interpretation. Let all things be done for edification” (1 Corinthians 14:26 RSV). It is difficult to conceive of instrumental music contributing to the biblical meaning of edification, building one up in the faith. It is more likely to interfere with the purposes of edification than to contribute to them. The type of vocal praise that evolved in the synagogue and the early church made
instrumental music irrelevant.
We are commanded to do the things God has authorized in His word (Col. 3:17; 1 Cor. 4:6; 2 Jn. 1:9; Rev. 22:18-19).
The apostle Paul and the Jews understood that God's silence is not authoritative (Heb. 7:11-14; cf. Acts 15:24).
God has not authorized instrumental accompaniment in the church. He has only authorized us to sing, accompanied by the string of our heart.
Mechanical instruments in worship were authorized by the Mosaic Law and the
Prophets (2 Chron. 29:25f). But God changed the law (Heb. 7:12-14); we live
under the law of Christ today (1 Cor. 9:21; Gal. 6:2; Heb. 5:9; cf. 2 Jn. 1:9).
God has not authorized mechanical instruments in the worship of the church (Eph. 5:18-20; Col. 3:16-17).