Has Christianity not lost its original message and purpose?

You need to remember not all Christians followed Rome or the Vatican. Millions of these Christians who refused to submit to the Vatican were murdered or persecuted for sticking to real Christianity during the dark ages. Today there are still Christians who refuse to follow mainstream Christianity, knowing full well that many customs such as Sunday, Easter, Christmas, etc. are pagan in origins. These Christians today who don't follow mainstream Christianity or Catholicism are not recognized by many in the Christian world as being real Christians, and are often referred to as "legalists," or "Judaizer," or at worst some even call them "cults" because they refuse to submit to Orthodox Christianity.