The Pater, or Lord's Prayer, is used by all Christians. According to the New Testament is the only prayer explicitly authorised by Jesus. Even here, there was scope for disagreement:
The Lord's Prayer - 1. We are all accustomed to hearing the line give us this day our daily bread. But the the meaning the Greek word translated as daily is unknown. Daily is just a guess. The Cathars claimed that they had preserved the correct meaning from earlier times. They said give us this day our supplementary bread, which arguably makes much more sense. The words in question (panis superstantialis or panem supersubstancialem) were interpreted as referring not of the material but of the spiritual sustenance.
The Lord's Prayer - 2. We are all accustomed to hearing the closing line For thine is the power, the power and the glory for ever and ever. But the Roman Church did not use this formula in the Middle Ages, which it claimed was an unwarranted addition to the text. Cathars were attacked for this innovation. As we know from its familiarity to us, it was later added to the Catholic form of the prayer, a tacit admission perhaps that the Cathars had it right after all.



