katlaughing & Stringsinger, thank you both for your comments.

Frank, your comment prompted me to return to this thread and prompted me to think about the influence of jazz on gospel music and vice versa.

I intend to post some links to several YouTube videos of gospel music that I think have a jazzy 'favor' to them. But first I need to confess that when you mentioned jazz singers, I didn't know which singer had the nickname "Sassy". Thanks to Google, I learned that "Sassy" was a nickname for Sarah Vaughn.

Here's a excerpt from an article about Sarah Vaughn's church background:

"With only vocal experience in a church choir, a young Sarah Vaughan set her sights on a singing career. It was on the stage of the Harlem Apollo Theater as a contestant that Sarah Vaughan launched her career. She was an untrained singer full of natural raw talent with the amazing ability to improvise and she possessed a three-octave range. By the end of her life, critics and colleagues recognized her as one of the greatest singers in the history of jazz.

Vaughan's Early Gift for Music

Sarah Vaughan was born in Newark, New Jersey into a musical family. Her father, a carpenter, played the guitar and piano, and her mother was a choir member at Mount Zion Baptist Church. Vaughan had a natural gift of music. Her parents nurtured her talent by giving her piano lessons when she was seven years old and organ lessons at eight years old. At twelve, she became the church organist and joined the choir.

Vaughan Gets Her Big Break

By the time that she was nineteen, her vocal talent was apparent. She was encouraged by friends to enter an amateur contest at the Harlem Apollo Theater. She entered, and won $10 along with the opportunity to perform at the Apollo. Jazz singer Billy Eckstine saw her performance, and introduced her to Earl "Fatha" Hines. She joined his band as a vocalist and pianist. Two years later, Eckstine asked her to join his band, which included musicians Dizzy Gillespie and Charlie Parker"...

http://afroamhistory.about.com/od/sarahvaughan/p/bio_vaughan_s.htm

-snip-

And while we're on the subject of African American singers who came from a church background, here's another excerpt from an online article:

"A good choir may have three or four really good solo singers. These singers eventually gained a following and typically formed a separate career fronting their own band. The the [sic] majority of the soul music performers of the 60s and 70s were former members of choirs. Aretha Franklin, Wilson Pickett, Otis Redding, Al Green, Roberta Flack, Solomon Burke, James Brown, and many more, all stood in front of congregations, dressed in robes, learning the ropes of one of the most demanding and intense vocal forms of music. Not all of the best talent left these choirs and turned secular. Mahalia Jackson, Shirley Caesar, and Albertina Walker to name a few, became highly popular soloists. Some of these soloists employ back up singers, or perform as guests with better choirs, but typically the soloist carries the song by her or himself."

Crosscurrents: History of Gospel Music

Also, see this excerpt from that same article:

..."Beginning in 1871 the black Fisk Jubilee Singers, who were students of the all black Fisk University in Nashville, Tennessee, traveled widely in America internationally with great success singing spirituals. Also, the late 1800s Ragtime was developing into what later a 1917 San Francisco newspaper music critic called "jazz" (alternately spelled "jass").

Gospel music had influenced blues and jazz, and now, by the early
1900s, blues and jazz were in turn, influencing gospel music. for
instance, the syncopated rhythms of ragtime firmly entered many of
church performers approach to existing and newer songs. Many
traveling singing preachers began to accompany themselves with piano
and guitar. The guitar became a popular form of accompaniment due to
the practicality of ease of mobility. Since blues pianists and
guitarists were common nationwide, the singing preachers began to
adopt the chordal and melodic styles of many of bluesmen and women.
Blues and jazz was the popular rage, and served as the spice for
black musical palates, while gospel was the religious staple.
The more theatrical and prosperous traveling preachers and performers sang in revival tents and as guests in churches and missions for the homeless. Many of them traveled with an entourage of musicians and small choirs"...

-snip-

I could post more, but my suggestion to those who are interested in this subject is to read the entire article.