I looked through a bit of Google, and found 3-4 different gospel songs with that title. Without the lyrics from these singers or groups, however, I don't know if one of them is for the song wanted here or not. I will try again later.
It does not appear in any collection of spirituals that I know of, and like WYSIWYG, I think it could possibly be an African-American gospel tune, 20th c. , but the associations of ideas in the song ring false to me.
The first two lines posted are floaters found in many spirituals, the trumpet sound is not uncommon, and there are echoes of material from a number of spirituals all through, but put it all together and it seems to be a mish-mash.

I like the image of Moses "smoting that water with a two by four." That does make it sound like a summer camp compilation.