This is a topic that occasionally arises among heralds and heraldry enthusiasts. I first ran into it as an idea way back in 1998, when I was presenting a paper at the International Congress of Genealogical and Heraldic Sciences entitled “Identity Through Heraldry In A Non-Heraldic Culture: The use of heraldry and quasi-heraldic devices by government, business, institutions and associations in the United States of America.” A copy of that presentation can be found on my website at www.appletonstudios.com/Congress1998DBA.pdf During the question-and-answer session which followed the presentation, one of the attendees made the point that the United States could not truly be said to be a “non-heraldic” nation, since it was a Christian one, the implication being that heraldry and Christianity were somehow linked together.
The topic has arisen again, this time in a post over on Kimon Andreou’s IDTG, his blog on “heraldry, genealogy, history and other things.” (I can highly recommend IDTG, and link to it has long been included in the “Other Blogs of Heraldic Interest” section of the left-hand column here.) In a post on October 6, 2011, he makes the argument that “Heraldry is not an exclusively Christian nor an exclusively European phenomenon” and gives both early and modern examples of why this is the case. (He even links, among other resources, to my own little article on Mamluk heraldry at http://www.appletonstudios.com/MamlukHeraldry2001.pdf and calls this blog “highly recommended,” for which I must - with all due modesty - thank him.)
If you’d like to read his take on whether heraldry is either exclusively Christian or exclusively European, or even if you’d just like to see the sources he links to there, that post can be found at: http://www.idtg.org/archive/1620-heraldry-is-not-an-exclusively-christian-nor-an-exclusively-european-phenomenon/