From Robert Johnson's alleged deal at a Mississippi crossroads, to use of the Diabolus in Musica, to tales of drinking and midnight creepin'... the darkness in the blues is there for all to see. But when was it first dubbed "the Devil's music"?
Shortly after the emancipation of black Americans in the United States, leisure activities were being demanded by this overworked and disenfranchised sector of the country. Juke joints, speakeasies and creep joints (brothels) specifically catering to the black community began to spring up in the Southeast to meet the demand unfulfilled by whites-only bars and taverns. These places became verdant ground for the evolution of black music. Ragtime, barrelhouse jazz, and slow drag dance, which was an early precursor to the popular contemporary "bump and grind" style of dancing, were all evolving with and along blues in these adult establishments.
A large sector of the black community were fiercely religious at the time, and criticized blues artists for subverting the gospel and spiritual tradition in the name of this secular and self-indulgent lifestyle music. The criticism came from all sectors of the "square" community, including of course, the white establishment. No one, it seems, wanted to acknowledge or accept what was going on in the underworld of black life. Black music had already for a long time been associated with evil influence, one of the earliest published denunciations found is from 1913, when The New York Times defended the fear surrounding ragtime music: "..decent people in and out of the church are beginning to be alarmed at the crude and vulgar music and loose conduct accompanying it with dances defying all propriety."
The stories and anecdotes that came from this underground community only fueled the fire. For example, the blues singer Son House was convicted for murder, allegedly shooting and killing a man that was shooting up a juke joint alongside his female partner. The legendary Lead Belly once escaped prison, murdered a family member, and stabbed a white man during a knife fight. Robert Johnson's life was shrouded in mystery, with his claim to fame, besides his amazing music, being a supposed deal with the devil he made in Mississippi.
Another integral part to this negative perception by the mainstream community was the drugs, sex and alcohol that infused the blues lifestyle. In the 1800's the word "blue" was slang for drunk, illuminating the tight link between this new style of music and the world of vice. The period between 1920 - 1933 saw the prohibition of alcohol in the United States. Black music suddenly found a lucrative niche, rubbing shoulders with the seediest sides of the country, while making money providing the entertainment in illegal joints. Blues artist have also traditionally written about drug use. For example Cocaine Habit Blues by Memphis Jug Band, Dope Head Blues by Victoria Spivey, Cocaine by Dick Justice, etc. Many artists were comfortable writing and performing sexually explicit songs, many of which were women, including Julia Lee, Dinah Washington, Harry Roy, Harlem Hamfats, Lucille Bogan, etc.
Personally, I see blues as one of the turning points of alternative culture. The true desires and needs of people were finally being celebrated, instead of denigrated or denied. It may be considered the Devil's music, but it was also the the Real Man and Woman's Freedom Music.