Hillsong music is simple, catchy, and easy to play. If a teenager can pick up a guitar and lead their friends to sing along with easy lyrics, it'll be a hit. A satirical take on this is How to Write a Worship Song (In 5 Minutes or Less). https://www.youtube.com/watch?v=GhYuA0Cz8ls Translations of Hillsong music into other languages are also popular. 約書亞樂團 Joshuaband translate some songs into Chinese, and it was a hug…
(A) Catholic (an example, for contrast) music tends to be institutional: choirs, organs... Formal. You don't just play the organ for fun, it's a scheduled, authorized activity. It's not something that spreads or something that exists outside of its preallocated box.
(B) Hillsong's kind of music is also accessible. You don't need much exposure to play or appreciate it. This isn't exotic tribal music, for and by some specific culture of people (think of Jewish kleizmer for example). It's pop, the stuff anyone can listen to or play.
Ie, you can tell from the music that Hillsong is new/modern, youth oriented, and mainstream-oriented and international/multicultural.
You can tell from catholic music that it's tradition and institution oriented. You can tell from Jewish music that it's tribally oriented. All ideological linchpins of those communities.