Before we go anywhere else, remember that just because they might not have been Christians, this does not mean that Druids did not believe in God. We tend to think that belief in gods precludes belief in God, but this is not necessarily the case. I'm sure some Greeks referred to Jewish angels as gods, and I know some early Christians took certain more illuminated ideas about Zeus to actually represent God. The idea that the Bible is the only way to find out about God is NEW.
That having been said, here is a review of the Wikipedia article on Druidism at
http://en.wikipedia.org/wiki/Druid. For each section, I give a short judgment on how accurate it seems based on my reading of book sources. "I don't know" means I cannot comment either way as to a section's/statement's validity.
Section above the table of contents: good
Overwiew: par 1,4,5 good; others less well founded.
Etymology: these are the usual theories; pay especial attention to the last 2 paragraphs
History: I can't vouch either way on this one.
Caesar: correct. Assume Caesar was not impartial, but less partial than a modern historian might be about an enemy. A complete translation of the section is at
http://classics.mit.edu/Caesar/gallic.6.6.html (Chapters 13 and 14)
Other Romans: I don't know about these. But Pliny is missing. His description of Druids is reported at:
http://www.sacred-texts.com/neu/celt/bim1/bim1008.htm but I cannot say how accurately.
Medieval Sources: this seems to be OK. The Welsh versions of the Arthurian legends are not here. They have a unique character which may at some level reflect the influence of druidical systems of "magic."
Social and Religious influence: probably too much fitting into modern categories here.
In Christian literature: Probably good. Notice the pre-"fundamentalism" lack of worrying about the names of things.
Late druidic survivals: I don't know.
Druidic Revival: I cannot vouch for all of these statements but those I have heard of or have read seem accurately reported. Unfortunately for modern "druids" the disconnection between today and ancient times is far greater than it is in Christianity, due to the general annihilation of the original Druidical oral tradition. One cannot count on most modern ideas of druidism being the same that ancient druids held. This may be a problem or not in itself, but there will always be difficulty in bridging the gap.
Modern druidism: don't know.
A possibly biased but detailed article on Druids exists at
http://www.lugodoc.demon.co.uk/Druids/DRUIDS.htm
This article has seemingly accurate and complete quotes from ancient sources. Its writer claims to be a druid but his history indicates that he is aware of the disconnect between ancient and modern druidism.
The entire heavily contested Barddas of Iolo Morganwg seems to be located at
http://www.sacred-texts.com/neu/celt/bim1/index.htm This is believed to be largely fantasy and is essentially the positing of a new philosophy that is probably not ancient druidism despite its name.
Just to stir the pot:
http://www.lugodoc.demon.co.uk/Lugodoc/rant03.htm
I don't necessarily agree with all that, but man, that monkey thing is a hard hit.
Sentio ergo est.