During the Settlement Era, and afterward before Planetary Unification, "Reptigan" referred to practical, secular, human-created decisions and habits and customs necessary for good governance and/or day-to-day survival, but not part of the holy principles of Adpihi.
From Planetary Unification to First Contact, during the Return to Space, "Reptigan" was used by those secularists who had begun to think that some of the tenets held by some forms of the Adpihi faith were either outmoded or dangerous or both, and that certain government offices and/or certain weapons should be kept out of the hands of those who adhered to such tenets.
Once non-Adpihians, especially non-Humans, had not only succeeded in being admitted to the Reptigan Union, but had made contributions that were recognizedly valuable, "Reptigan" began to mean that Union and its member states and their citizens. Until that time there had been tension between that Union's tendency to become an Empire and its tendency to be a "federal" Union; after that it was, in its own eyes, definitely a Union rather than an Empire.
But, after they had re-established contact with Earth, it became an important point that not everyone -- including especially not everyone in Earth's sphere of influence -- regarded the Reptigan Union as completely free of imperialism.