I am, as I'm sure you know, a Christian. I'm hardly looking to become a pagan; you're right if you think I want to argue against paganism, but that doesn't mean I'm not interested in your information. I'd rather know what your actual position is, instead of getting everything wrong and looking stupid.
Celtic paganism: A few more sources than I thought at first, but hardly enough to say that almost nothing was lost. The main sources are the ones I already mentioned, Roman writers. Inscriptions and archeological evidence can tell you that this particular god was worshipped at a particular site, but not about what doctrines were held. If I'm not mistaken, Julius Caesar wrote that the druids kept everything memorized, not written down. If that's true, almost everything was lost.
Norse paganism: Trying to reconstruct Norse paganism from the Eddas and Pliny can be compared to trying to reconstruct Greek paganism from just Homer. You could do it, but there's a lot of other stuff. How do you know you haven't lost something important?
Of course, if you expect that proving you do have all the necessary information won't persuade me, you're right. No one would dispute that Hindu(or perhaps I should say Aryan) paganism has everything now that it ever had, and I'm not Hindu. There's still a question you would have to answer. Why should I believe that the native religion of a particular people has a claim to truth that other types of paganism and the later religions don't have?
That was one of the points I was tryin' ta make. No one group of people can lay a claim to the Absolute Truth. It is the one thing that NONE of us will know until we are dead.
Over eons, all types of information about earlier times has been lost. Who can say for certain that all of the info we have on Christianity is 100% accurate? How many times has the Bible been re-writen, sometimes by those with questionable motives? What about the Gospel of St. Thomas found near the Dead Sea that the Vatican rejects as heresy? What other bits did they leave out?
As for the Celts and the Norse, just because I only listed a couple of really quick sources, do not think that this is all there is. That'd be like saying that the only thing we know about Christ came from the Council of Nicea. Oral traditions gave way to more permanent methods of recording. Leaf Books, ogham script, and pictitorial enscriptions all have played a part in preserving quite a bit of the beliefs of those cultures. Not to mention the writings of middle eastern visitors and teh Romans.
As for what my personal faith should mean to others, nothing. I live my life as I see fit. I don't have the moral authority to tell others how to live. If my "leadership by example" makes others curious about my beliefs, I'd be happy to share my viewpoints. Forcing someone, through government interdiction or otherwise, undermines any moral stance I could have claimed.
Forcing someone to believe something I want them to negates any responsibility they may have had in making that decision. The ultimate, "The Devil made me do it" type of dodge.