I have to say I’m bloody impressed that someone remembered my religious affiliation.
We actually do know a fair amount about the ritual practices of the ancient Egyptians – they wrote every damn thing down they could, including on the walls of temples (many temples are illustrated with appropriate practice for the rooms; several incense recipes were also recorded – though we’re not sure what all of the components are in some cases). What we don’t know about are the sorts of practices ordinary people did in their homes – which means that moderns trying to do roughly the same thing strip down what we can puzzle out about the temple rituals and fake it from there, which may or may not be a good guess at all. (And that’s without getting into the endless pissing matches about what parts of what we know of ancient practice are essential and how many of them are bound to the time, what level of authenticity is appropriate, what should be used to patch the gaps …)
At the other extreme, Celtic recons are pretty much screwed, because their religious types figured that the best way to keep religious practice sacred was to never write down any of it. The closest we have to records of Celtic practice was written down by monks who were interested in local folklore. My boyfriend (who has CR leanings) doesn’t believe reconstruction is actually possible, because there’s too much “gotta make some shit up to fill in the knowledge gap” involved.
Responding to fetus: The problem with “could call yourself Wiccan if you wanted to” is a fairly current and active one in the relevant communities. “Wicca”, strictly speaking, has to do with initiatory lineage from Gardner and the training that comes with it; a lot of the people who have that history are extremely frustrated with the loss of the term to some form of generic neo-paganism that doesn’t touch on the essentials of their religion. A lot of the people who came to Wicca from book learning or eclectic groups are offended by the strict meaning, because they feel it’s an attempt to take their religion away from them. This is sort of one of the standing wave pissing matches that occasionally one comes across. (I am getting more inclined to stricter definition as time goes by as I’ve gotten more familiar with religious witchcraft that is not descended from Gardner at all.)
One of the big differences between many of the modern pagan religions and a mainstream interpretation of what ‘religion’ means is that they are, like most tribal religions, orthopraxic, not orthodoxic: for the most part, correct belief is not a big deal. Correct behaviour – doing the right rituals/ceremonies/prayers, behaving according to community/tribal standards, etc. – is the big deal. This means that you’ll get a lot of pagans, even of the same religion, spouting off about a huge variety of different beliefs, which can lead to an impression that anything goes – the actual practice stuff doesn’t turn up when people are nattering on on message boards.