Here's a YouTube posting of Washington Phillips' remarkable original version of Denomination Blues, from the 1920s:
The sweet-sounding instrument backing the song was apparently known as a dulceola but nobody quite knows what it was.
Parchment's second version of the song, recorded as the opening track on Shamblejam and familiar to quite a lot of people, is probably closest to this, relying as it does on John Pac's raw vocals and the simple mandolin accompaniment. The version that has emerged on the lost album
Phillips recorded two "parts" to the song. This part is Part I and doesn't include the notable line: if you ain't got Jesus, you's an educated fool.
More samples can be found at one of the labels that has released his songs on CD.