Yes, I think they can be. There is a discussion somewhere about english harmony singing and how it originated in the church. Some LDS (mormon) hymns sound very folkie to me.

Then there's some of the christmas songs, like "Brightest and best". And some hymns have been turned into protest songs, like "Power In the blood"/"Quartermaster's Stores"/"Industrial Union Grand(?)" Joe Hill got some inspiration from hymns.

Just a little thought ...

Teresa