I say "part 1" because I imagine that I'll have a lot more to say about this in the future. For now I'll simply suggest that the Church seems ill-served when less attention is given to selecting music leaders than teaching pastors. The music in a church is so reflective of that particular community's faith confession, so symptomatic of its desire for excellence in offering praises to their God and so influential in their development of genuine devotion that the music leader's influence with the congregation is often rightly second only to the senior pastor. Some would disagree with this assessment, but I am persuaded that these two positions (senior pastor and music leader) are the dominant catalysts to peoples' faith response to the Sunday morning service.
It is out of an understanding of sacred space, sacred days and sacred times that we rightly acknowledge the importance of Sunday morning to people's religious experience. Perhaps in other cultures the standard meeting day and time differs significantly. However, in the U.S. Sunday morning is the received practice. In addition, the sense of sacred space drives people to expect an experience with God at church that differs from that which is enjoyed during the rest of the week and everywhere else. This notion of the sacred can be overblown of course, resulting in the worst expressions of legalism in practice during the Roman Catholic era of the Church. On the other hand, to deny the human attraction for the sacred is to deny the human's need met by Old Testament prescriptions for worship and sacrifice to Yahweh in the Tabernacle or the Temple.
As a result of understanding and appreciating the sacred, we can see that those that lead a band and congregation in the singing of praises on Sunday morning are "instrumental" in helping the sacred event have the proper religious effect for the participant. In other words, he does with art and music what the pastor hopes to do through preaching of the Word and the administering of the sacraments. They have different methods, but parallel goals. For this reason churches rightly undertake to examine potential music leaders with a scrutiny only slightly less rigorous that they would another pastor. What is their theology? What is their doctrinal makeup? What do they believe is the role of music in the Church? Do they have a well developed philosophy of church music? How do they believe that doctrine and art must coincide? How is the transcendent church celebrated through music? How can multiple generations be kept together in one service through musical diversity? How does their knowledge of the sacred effect their playing?
These and many more reasons combine to suggest that music must be pursued as a priority of the Church's faith expression second only to the exposition of the Word of God. In addition, church leaders had better approach the selection of music leaders with sober reflection that takes into account music's timeless importance to the community of faith. Once having made such a choice, satisfied that the above mentioned concerns are well addressed, the leadership of said musician must carry the weight of the process that the church's leaders went through to appoint him. This weight is appropriate because the issue of whether of not he could play an instrument well was the last concern to be addressed. The foremost concerns that the leadership had better have addressed was whether the music leader can well assist in the leaders' vision of what manner of sacred event that particular church must pursue. If the selection is a fit, then the music leader leads with the credential of having been selected by the church's leaders, and by extension, having been appointed by God for that task. Such is the importance of music for expression of the sacred in community.