Is it sinful to use musical instruments in church?
Answer: There are many references in the Bible to God's people using music instruments to worship Him. For example: David made many musical instruments and organized music for the worship of God (1 Chron. 23:5; 2 Chron. 7:6; 29:26; Amos 6:5). Solomon made musical instruments (1 Kings 10:12; 2 Chron. 9:11; Eccl. 2:8). In Revelation 14:2-3 the angels use harps in praising God. So it is clear that God approves of musical instruments in worshiping Him.
There is an article at http://mywebpages.comcast.net/wheelerjw/MITB/MITB.htm which address the use of musical instruments in the Old Testament.
Another article is found at http://www.learnthebible.org/music_in_the_new_testament_church.htm which discusses music in the New Testament church.
There is nothing evil or sinful in an instrument itself, nor anything spiritual. It is merely an instrument. However, how it is used can be spiritual or evil. There is nothing spiritual also about saying that musical instruments are sinful and should not be used. God in no passage in the Bible says such a thing. He gave no law concerning use them or not. He did allow them when properly used as the OT shows.
So no one can truthfully say they are spiritual because they use or do not use an instrument.
There is nothing spiritual about singing without instruments either. Many singers take great pride in their ability to sing. Even in congregational singing often you hear some who makes a point of singing loudly above others to be heard. The same applies to solos and groups also. Some folks have no stage but their church who allows them to perform. Singing without accompaniment can be sinful if done with pride as can using musical instruments be misused.