[Varda]

""You can only imagine what these people were thinking to be put to work painting a wall with completely alien symbols," Blind said."

Maybe they were thinking they were honoring Christ their Lord and Savior.

This assumption that the Indians couldn't possibly have done this for their own reasons is common among archaeologists. I visited the British Museum last summer and wandered over to their North American exhibit. There among the artifacts was a letter by a newly Christianized Indian from one of the California missions. He explained that life was better now that he lived at the mission. The English of course in their hatred for all things Spanish and Catholic couldn't let that stand unanswered so they had a modern interpretation beside the letter explaining that the Indian was a slave. They did that for nothing else in that exhibit.

[expat_panama]

English of course in their hatred for all things Spanish and Catholic

The Brits also have a very strong doctrine of "Yanks were always bad to the red-indians".  It distorts much they write in science, news, history, literature, etc.