The proper etymology of Druid is Annointed One... the Oak stuff is mostly the early revivalists getting bogged down in the fact of oak reverence of the Druids. Peter Berresford Ellis makes a strong case for this, and earlier names for druid before linguistic drift back him up, which 17th century druid clubs didn't account for.
I thought Catholicism was pagan christianity. 400 saints instead of 400 gods and goddess... all the festivals and rituals they took over... Those letters from Pope Gregory telling everyone to sanctify pagan practices to the use of God. I don't know much about christianity apart from some of the basics though, so feel free to correct me. I see it as a good thing, that they converted without wiping out an earlier culture myself.
St Bridget and her types took over the pagan cult of the nine maidens, giving a patriarchal religion a safe outlet for reverence for the female.
St Patrick... not so sure. I think it was a spin campaign, replacing magic with miracles. Like when they say he banned the snakes from Ireland, he was banishing the evil worship of Crom the red serpent, and the more benign worship of the white serpent Nethy in a metaphor of banning snakes. Might also refer to the banning of the "serpents of wisdom" as druids supposedly called themselves.
As for magus, the word was used for anyone doing magic, from druids to saints, wasn't it?
