Most, if not all, religions have basic principles. If they did not have these each individual religion would cease to exist. One could not describe oneself as being a Jain who believes Jesus died for our sins and rose on the third day and believes in heaven and hell, because this violates those Jain principles and would just make on a Christian.Who is the "Final Authority" for each belief system?
I fail to see how, outside personal preference/beliefs/interpretations how anyone can make an "official" declaration.