I haven't seen anything I consider authoritative to indicate that Plenn's grandmother was a Quaker. Since Sandy says the whole Quaker thing was Pete's mistake, I see no reason to give creedance to that idea.

I have no idea about the quote, but the description of the Grandmother is where Quakerism is mentioned, not in the quote itself.

But why the obsession with trying to make it a Quaker hymn?

Robert Lowry is cleary responsible for the tune, along with many other popular Gospel songs. The words are 'source unknown.' Could be Lowry, or he got it from someone else. Hymnologists have not been able to find anyone else to credit.

It was republised many times in the late 19th century. Dorothy Plenn's family seems to have kept singing it even as it may not have been constantly included in later Gospel song books. Her grandmother could have believed anything about the song. That just tells you what gave it meaning for her, not where it came from.

Given the date of 1869 indicating possibly the 1860's for it's writing, I'm inclined to read it as song about the tumult of the Civil War. Life can be full of tumult, though, so how one identifies with the words can be very individual & personal.