Thanks for the swift and thoughtful reply.  Everything in the first part makes sense, and to the second part I really like option 1.  "The Gregorian calendar is the predominant calendar in international trade and communication" is succinct in your correct analysis of leaving out a trace of religion to avoid conflict.  It lacks any POV of preference in personal life and religion; it is a fact rather than truth.  I'll take it, but wait a bit to see if or when others chime in.  Two makes consensus naught.  I'll check back in a day or two to see what has developed.  Happy editing to you.  talk