Two of our greatest singers---Sam Cooke and Aretha Franklin---came from the Gospel world, and were denounced by the flock for their heresy---performing secular music.
Prior to modern times (sometime in the 19th Century, I believe), Classical music---music that has survived for one reason because of it being notated---was purely the music of the Aristocracy, the Kings etc. who were it's patrons. Composers were employees, and wrote the music needed for official ceremonies, as well as for the entertainment of the Royals, who were themselves often amateur musicians. J.S. Bach's day job was as a church organist, and his organ works were written for the Sunday Masses. That they survive as art is incidental!
The music of the proletariat was not written down (notated), but was passed down from generation-to-generation, sitting around fireplaces, at dances and taverns. The songs we now think of as "Folk" music (in not the literal, but rather largest sense of the word) survived by being kept alive by troubadours, traveling minstrels, etc. It was not until A.P. Carter, June Carter's Grandfather (Carlene's Great-Grandfather) notated and copywrote the songs he had grown up hearing the hillbillies in Tennessee singing (music brought to America by the English, Irish, and Scottish, mostly), and subsequently recorded by The Carter Family (considered the First Family of Country music), that that rural music made it out of the mountains and into the cities and towns of the rest of the U.S.A. and beyond. It is that Folk music that was one half of the recipe for making what became Rock 'n' Roll (see below).
It's not hard to understand therefore that at some point people look back, and embrace and celebrate that Folk music, later known as Hillbilly, Country, Bluegrass, Western Swing, and finally, which when mixed with the music brought to America and developed by African slaves and their ancestors---Blues, became Rockabilly---the first integrated music! It was that integration that first got Rock 'n' Roll banned by racist southern whites, who didn't want their kids listening to no n*gg*er music, even if it was being performed by whites (Elvis, etc.).