This is a question about the custom of honourifics.
Many religions have customs of repeating honourifics when mentioning God or the departed. Probably most notable are Judaism and Islam. In Judaism we it in such cases as saying “Blessed is He” when mentioning God, “May peace be upon him” when mentioning an ordinary human, “May the memory of the saintly be for blessing” for saintly persons and martyrs, etc. In Islam we see it in such cases as saying “Glorious and exalted is He” after mentioning God, “May God bless him and grant him peace” after mentioning Muhammad, “Peace be upon him” when mentioning other prophets, etc.
The use of honourifics seems to a standard rule of etiquette among Semitic cultures. That is, there is a stress on honouring God and deceased person with the honour they are seen as deserving. As we all know, Christianity is a continuation of the ancient Jewish religion, and arose in the same region of the world, its early followers being Semitic. It then seems logical that there may have been such honourifics used by Christians. Maybe not by all Christian, but I would think it likely that at least the Christians that were Jews, Chaldeans, Arabs, etc. would have had them.
The only one I could think of, however, was the use of “may his/her memory be eternal”, used after mentioning a deceased loved one. Does anyone knows of any other honourifics that Christians used, or have used, for God, prophets, saints, etc.?
Also, is “may his/her memory be eternal.” usually only used for loved ones and relatives, or do people use it for the deceased in general?
Thank you for you help,