"I'll Take You There," by the Staple Singers
Singing isn't my new religion, but I love it infinitely more than I do my old one (I find it infinitely more useful, too). And I think I get the use of "soul" when it comes to singing (and playing): it's artful and sincere, it makes you and the singer(s) and player(s) ecstatic or sorrowful (mostly the former, in my experience) . . . Heck, I'm just running my mouth . . . Listen to this song, its soulful lyrics, its soulful players, its soulful singers, the soulful woman singing lead . . . You'll know what I mean.
(Of course, the joke's on me because I think they're all talking about heaven, and I don't believe in heaven.)