Realist,
This subject matter would take volumes of post's to give all the information. There are dozens of books on the subject that give thousands of references. I'm not sure of which splinter group you are speaking of but you may be referring to the Gnostics. They are the ones that many claim to have written several more gospel accounts of Jesus than the four that were chosen to show up in the bible.
Just as anything throughout history events and stories are changed by those who are trying to portray their personal view and beliefs. Every religious faction writes books and literature to try and expand on what they feel is the accurate. The bible as many old religious books have been manipulated and crafted to fit specific dogma. Various religions then take what they feel the bible says and give their own interpretation of it's words.
History and archeological evidence point to one thing and religious propaganda points to another. When Religious propaganda mixes fragments of history with unprovable myth you end up getting what you have today. Speculation and faith based on individual interpretation and personal desire are what all religion is based on.
The stories of Krishna and Buddha were written hundreds of years before Christ supposedly walked the earth. Some of the stories of both previous god-men read almost word for word as stories in the bible.
One that struck me as absolut plagiarism is the story about the woman who's son dies and she asked Jesus to help. He sent her out to find a household where they had not lost a loved one to death. She was told to get a mustard seed from every family who had suffered this loss. She came back with a hand full of mustard seed. This story was written almost word for word about Buddha hundreds of years before the same exact almost word for word story was written about Jesus.
There are hundreds of similar stories that match. You can figure out the rest yourself. Personally my days of research on this issue are over. I simply do not care anymore. It's all bullshit to me.
Dave