The document discusses the Greek word "psallo" which is translated as "sing" or "make melody" in various Bible translations. It provides definitions of the word from Greek lexicons which indicate it means to pluck, touch, or twitch strings. The document also argues based on these definitions and consistency principles that when Paul commands believers to "address one another in psalms and hymns and spiritual songs," he intends it to mean singing without musical instruments. It includes several quotes from religious leaders expressing reservations about the use of instruments in worship.