The article discusses whether Xu Guangqi was the author of the book "Tie shizi zhu," which promoted the Iron Cross as a Christian Relic in China. It states that there is a discrepancy between the dates of the discovery of the Xi'an stele in two of Xu Guangqi's works: "Tie shizi zhu" dates the discovery 1625, while "Jingjiaotang beiji" dates it 1623.