When we were in St Ives a few weeks ago we went to the Tate - like you do. There was a great exhibition on at the time (it's still on) called 'If Everybody had an Ocean' based on the life and music of Brian Wilson from the Beach Boys.
Anyway, one of the artists whose work was featured in the exhibition was a new one on me - Sister Corita Kent. She was a Catholic nun and quite an extraordinary graphic artist who was quite prominent in the 60's counter-culture. Someone said that she did for bread and wine what Andy Warhol did for Campbell's tinned soup. I was quite taken with the pieces of hers that were in the exhibition and particularly with the way that her faith, art, and the counterculture blended to produce some striking results. For example, how's this for an altar piece:
or this....and here are some of the nun's from Sister Corita's community in production...
Anyway, if this flips your widget you can find out more about Sister Corita here or purchase an art book with lots of her stuff in on Amazon.