IIRC, the last cut on the eponymous "Vanilla Fudge" album was a jam session where each of the members recited something, and Mark quoted Deuteronomy 34, the passage about the death and burial of Moses. I've always assumed that there was something religious behind at least some of what they did.
Mark is a Jew-—how observant, I don’t know. But I think he was the driving force behind them doing “People Get Ready.” BTW, as good as their version is, listen to Jeff Beck’s instrumental version of “People Get Ready.” Cry every time.