Well, Paul never even met Jesus, while Peter and James knew him well, so can you blame them for assuming that they were more "qualified" to judge and interpret? The story I learned about this went something like this (I hope I get it right): in order to get more recruits for the new Christian sect, Paul decided to "ease" the requirements by first starting to accept gentiles, which wasn't done before. In order to attract even more new recruits, Paul cancelled the dietary laws and the circumcision laws ( from what I understand that one was a big deterrent!
) among some other original rules, and generally tried to taylor the new rules so that they appealed to the general public more. After he adjusted these things, a lot more people started to flock to him. The other apostles, like Peter and James, were none too happy with this - they felt that Paul is only adjusting things in order to be popular/get more people in, so this is why they renounced him. So according to this view, although orthodoxy may be the oldest out of the three sects, it is by no means the original, since even Jesus himself did not seem to follow the current version (his was pre-Paul)...
I am not by any means an expert on any religion, I just happen to remember this story I once read. I hope this doesn't offend anyone as it is meant purely for discussion purposes. But for me, finding out things like this makes me wonder about the authenticity of any religiouos sect...
Yes, seems that we could use a section on religion here! 
I've got just an undergrad minor in religion but it continues to fascinate and I try to keep up on the new scholarship. Paul's whole point in "easing" the restrictions had to do with his belief that Jesus himself wanted it that way. I do believe that Peter, James, et al were behaving like silly twits, Peter was beyond a shadow of a doubt a huge hypocrite and James only joined in the "show" when he realized there was something in it for him (in this world, that is

). During Jesus' lifetime he was opposed to his brother's ministry to the point of (along with other family members, including Jesus' mother) attempting to basically have Jesus committed or at least keep him from continuing to make a bad name for his family.
As for the original faith, Jesus cannot be the originator of the religion since (at least according to the gospels, which are at the VERY least, highly suspect) he never intended to start a new religion of any type. As far as any officially organized Christian religion, Orthodox *is* the earliest example and it was based on the practices of the "house churches" established around the region by Paul.