When Christianity was the only religion, all other theologies were declared heresy, except for Jews, of course. But all other religions were heresy.
In our day we have exactly the same phenomenon. All political positions which are not Politically Correct constitute something called “the right.” “The right” includes groups as disparate as the Heresies of the older established religions.
A Buddhist would have laughed at the idea that he was the same as a Shintoist. He would, rightly, consider anyone who said that as a total rube. But when you have an established religion, you are an intellectual hick.
In fact the best way to be sure a people has an established religion is to note that nobody even notices that their language puts everyone who is not Of The Faith into a single category.
The established religion seldom calls itself “the left.” But everyone understands that all opponents of the established faith constitute something called “the right.”
Everyone who denies God in the name of science is called an atheist. But astrologers were also accused, often correctly, of being atheistic. They considered astrology to be a science. Hence the more dedicated astrologers denied the power of any gods because it was the stars that determined everything.
This was a very serious split in its time, but we can’t even see it, because to those of our present established religion as to every other established religion in history, all who are outside The Faith are the same.
As Zoroastrianism began to admit non-Aryans in its latter declining days, it also lost faith. The Magi became more and more astrologers, the science of the time. So today the Wise Men were considered astrologers, and may well have been.
These distinctions become totally lost in a society that has a really established religion, as we do. The mind actually rots intellectually.
Mantra thinking is really the only thinking that is really outside the whole suffocating and wide spread chokehold of the religion of Political Correctness.