Give me Oil in My Lamp

So the Nurses had their annual graduation for the Nursing School. It was fairly uneventful for the most part: nice things were said about various people (most of whom deserved to have nice things said about them), and speeches were made about how needed these Nurses are (not that the Hospital will hire any of them; they hire their Nurses from the South).

At one point when all the Nurses were lining up to have Nursing Pins pinned on them, some of the other nurses (see picture below) began to sing, in a rich, thick accent belying their lack of native English, "Give Me Oil in My Lamp."

Huh? Where did that come from?

One of two of them are Christian, but I am wondering how the rest got roped into singing the song. Granted, it is not particullarly Christian song, and they modified the verses to make them even more generic ("Give me Service in my Heart, keep me helping, helping, helping..."), but "Huh?'