Here's the part I like best in the little bio about St. Brigid of Kildare:
Kildare had formerly been a pagan shrine where a sacred fire was kept perpetually burning, and Bridget and her nuns, instead of stamping out the fire, kept it going but gave it a Christian interpretation.
Brigid herself was named, evidently, for the pagan goddess of healing by her druid father. Thus saith Wikipedia, anyway.
I don't know. I find something touching about all of this: that it's not, "This is evil and must be rooted out!" but "This is God's and should be loved and cared for."