Summary: Looking at the history and scripture concerning music in worship.
Worshiping God in Song
Speak to one another with psalms, hymns and spiritual songs. Sing and make music in your heart to the Lord. (Ephesians 5:19)
So what shall I do? I will pray with my spirit, but I will also pray with my mind; I will sing with my spirit, but I will also sing with my mind. (1 Corinthians 14:15)
Let the word of Christ dwell in you richly as you teach and admonish one another with all wisdom, and as you sing psalms, hymns and spiritual songs with gratitude in your hearts to God. (Colossians 3:16)
"There is no record in the NT of the use of instruments in the musical worship of the Christian church" (Wycliffe Bible Dictionary, Peabody, MA: Hendrickson, 1998, p. 1163).
"Whatever evidence is forthcoming, is to the effect that the early Christians did not use musical instruments" (William Smith & Samuel Cheetham, A Dictionary of Christian Antiquities, London: John Murray, 1880, II, p. 1365).
2nd 3rd & 4th Centuries
Tertullian (c. A.D. 150-222) spoke of those who contended that "the thing which is not forbidden is freely permitted." He replied: "I should rather say that what has not been freely allowed is forbidden" (Ante-Nicene Fathers, Peabody, MA: Hendrickson, 1995, Vol. III, p. 94).
Chrysostom ( 380 AD) had to disclaim against the secularization of church music. More lasting was the opposition to the introduction of instrumental accompaniment." (John Kurtz, Church Music)
5th - 8th Centuries
Lyman Coleman, an outstanding Presbyterian scholar, wrote, "Both the Jews in their temple service and the Greeks in their idol worship were accustomed to sing with the accompaniment of instrumental music. The converts to Christianity must have been familiar with this mode of singing, but it is generally admitted that the primitive Christians employed no instrumental music in their religious worship."
The American Encyclopedia, Vol. XII, p. 688 says, "Pope Vitalian is related to have first introduced organs into some of the churches of Western Europe about 670; but the earliest trustworthy account is that of one sent as a present to the Greek Emperor Constantine Copronymous to Pepin, king of the Franks, in 755."
9th - 14th Centuries
The Encyclopedia of Religious Knowledge, in an article by J. M. Brown, page 852, adds, "That instrumental music was not practiced by primitive Christians is evident from church history. The organ was first introduced into the church service by Marianus Sanatus in the year 920; and the first that we know in the West was one sent to Pepin by Constantine Copronymous about the middle of the eighth century."
Archaeologists are generally agreed that instrumental music was not used widely in churches till a much later date; for Thomas Aquinas, A.D. 1250, has these remarkable words: "Our Church does not use musical instruments. . ."
The several general periods of religious history, from the close of the New Testament until the present, have been searched many times from many viewpoints. These searches yield one significant fact, which is clear and unassailable: Instrumental music in worship within the church professing did not emerge until hundreds of years after the close of the New Testament.
John Calvin, the founder of a significant strain of the reformed churches, in his Commentary on the Twenty-Third Psalm, said, "Musical instruments in celebrating the praises of God would be no more suitable than the burning of incense, the lighting of lamps, and the restoration of the other shadows of the law."
John Wesley, founder of Methodism, puts it this way, "I have no objection to the organ in our chapel, provided that it is neither seen nor heard."
The "Little" Word that Means So Much
"The word psallo originally meant to play a stringed instrument with the fingers, or to sing with the accompaniment of a harp. Later, however, and in the New Testament, it came to signify simply to praise without the accompaniment of an instrument" (Vine)
In his popular work, Word Meanings in the New Testament, Ralph Earle comments on psallo in Ephesians 5:19. "Making melody" is one word in Greek, psallontes. The verb psallo meant first to strike the strings of a harp or lyre. Then it meant to "strike up a tune." Finally it was used in the sense "to sing" (p. 333).
The meaning of certain words can and do change over time. One example from modern English will suffice as an example of this, gay. The Greeks experienced this with psallo. The first meaning of the word psallo was used as an archery term meaning to pluck the string of a bow. Later this word was used in reference to plucking the strings of an instrument. But sometime around the first century the meaning changed to simply sing without accompaniment.