Baldwin uses gospel and secular music, jazz, to emphasize key points in the play. Jazz is positioned as evil or bad in comparison to good gospel music. However, over the course of the play, it becomes clear that nothing is as simple as that. The so-called "good" gospel also veils the hypocrisy of the protagonist, Sister Margaret, who—in her pursuit of good or a spiritual life (represented by gospel)—abandoned her husband, who is represented (in her mind) by jazz.
The BBC says that jazz developed, in part, as the music played in brothels:
Early jazz pioneer Jelly Roll Morton, whose own name was a euphemism for sex, first developed his own style playing piano in these "sporting houses" and to get extra tips he’d peek at a prostitute and her client through a peephole and time his playing with the pace of their revels.
Not surprisingly, on the surface, Baldwin positions jazz in diametrical opposition to the more (seemingly) spiritual gospel music. Sister Margaret, who is the pastor in her church, embodies the negative views of jazz, which represents the secular world. However, Baldwin wants to tear away Sister Margaret's hypocrisy to show that both forms of music can be joyous and uplifting.
Although she is loved by her congregation, Margaret is also somewhat priggish throughout most of the play. She has rejected her estranged husband Luke. In part, she blames the failure of their marriage and tearing apart of their family on his commitment to jazz. She says accusingly to Luke:
You was always on the road with them no-good jazz players.
However, Luke disputes Margaret's comment that jazz destroyed their family. Moreover, it was the loss of his family that ruined him.
Music also sets the tone of the unfolding story in the play. For instance, at the end of the play, after Sister Margaret’s secret has been revealed and she has reconciled with Luke, the final song in the play is one “of jubilation.”