The term Gospel music may refer to either (strictly) religious music that emerged in the African-American churches in the 30's and to the religious music composed and played by artists of any ethnicity of the southern States.
The separation between the two styles, in fact, was never absolute: both come from the tradition of Methodist hymns.
However, even if some songs are drawn from a school on the other, the sharp division between black America and white America and between the black church and the white church, kept the two current uniforms. Although these divisions are slightly loosened in the previous 50 years, the two traditions are still distinct.
In both traditions, some artists, such as Mahalia Jackson, they just appear in purely religious contexts (Gospel Gospel means in English), while others, such as the Golden Gate Quartet and Clara Ward, also singing in nightclubs.
Most of the artists, such as the Jordanaires, Al Green, and Solomon Burke tends to play in both contexts. It is common that include a religious piece in a secular performance, although it does not happen almost never the reverse.