Short answers, pulled from the story.
Pope Gregory I issued the directive in the year 590. This directive standardized the notation and performance practices of Gregorian chant across the Catholic Church. The resulting monophonic unaccompanied vocal style became the bedrock of Western liturgical music for over a millennium.
The first Protestant hymnal was published in Bohemia in 1532 by the Unitas Fratrum. This publication marked the beginning of the Protestant hymn genre which prioritized congregational participation and vernacular language. The Reformation also spurred the creation of metrical psalters such as the Genevan Psalter and the Scottish Metrical Psalter of 1650.
Composers Johann Sebastian Bach and George Frideric Handel wrote vast bodies of work that elevated the organ from a simple accompaniment instrument to a solo voice. The Baroque period established a legacy of instrumental excellence that continues to influence classical Christian music to this day. Composers like Olivier Messiaen and Louis Vierne carried the torch of the organ repertoire into the modern era.
The Christian music industry began to take shape in the 1970s as a parallel structure to the general music market. This development created a near-billion dollar enterprise that supports a vast network of artists, producers, and educators. The Gospel movement gave rise to this industry which remains a vital force in Christian music today.
The Ichthus Music Festival started in 1970 and began to draw crowds of up to 100,000 people. This festival exemplifies how Christian music moved beyond church walls to be played in concert halls, clubs, and outdoor venues. The genre expanded to include subgenres such as Christian metal, Christian punk, and Christian hip hop.
The hymns of Jehovah's Witnesses are translated into upwards of 500 languages. Their organization maintains an extensive network of recording studios and skilled sound technicians around the globe to ensure that the songs are performed and recorded in as many languages as possible. The first song of this type, Give Me Courage, was released at the 2018 Be Courageous Convention and the second, Give Jehovah Glory, was released at the 2024 Annual Meeting.