Behind his head are the two Greek letters chi and rho and that tells me at once who he is, because they're the first two letters of the word Christos, and this is in fact Christ.

头部后方还有两个字母chi和rho, 这让们立刻了解了这名男子的身份：这是christes的首字母，而们所看到的正是耶稣最早的图像之一。