From Invoking Animal Magic:
There are a few positive Christian legends about spiders. In one story, spiders decorate the Christmas tree with their webs, which is why tinsel is applied to holiday trees today. In another a spider spins a thick web over the cradle of Baby Jesus to hide him from the wicked King Herod. Since Christmas is the most pagan of Christian holidays, it seems reasonable that some pagan solstice stories about spiders became woven with Christian themes.
Happy Holidays everyone!