What is this imago dei anyway?

The notion of the “image” doesn’t refer to a particular spiritual endowment, a secret “property that humans possess somewhere in their genetic makeup, something that might be found by a scientific observation of humans as opposed to chimps. The image is a vocation, a calling. It is the call to be an angled mirror, reflecting God’s wise order into the world and reflecting the praises of all creation back to the Creator. That is what it means to be the royal priesthood: looking after God’s world is the royal bit, summing up creation’s praise is the priestly bit. And the image is, of course, the final thing that is put into the temple (here I draw on John Walton’s careful exposition of Genesis 1 and 2 as the creation of sacred space, and the seven days of Genesis 1 as the seven stages of temple building), so that the god can be present to his people through the image and that his people can worship him in that image.—The Lost World of Adam and Eve, p. 175