The Hebrew for “image” (tselem) comes from a “root meaning to shade; a phantom, i.e. (figuratively) illusion, resemblance; hence, a representative figure.” It is used in several Old Testament passages for idols (e.g., I Samuel 6:5). This point is emphasized by Robert Luginbill, professor of classics at the University of Louisville, who argues against any effort to eisegete the term: It “means ‘image’ in a fairly concrete sense; the word is often used for statues of pagan idols which, after all, are meant to be exact replicas of the god in question.”
“Likeness” (demût) means pretty much what it does in English – like something, but not the thing itself. As the theologian Gordon Wenham notes in his commentary on Genesis, the terms are used interchangeably in the Bible’s first book (for an example, see Genesis 5:3). John Piper summarizes, demût “is used uniformly in connection with a tangible or visual reproduction of something else. So again, as with tselem, the usage of demût urges us very strongly in the direction of a physical likeness.”
Just as a statue is not the thing it represents but is identifiable as an artifact resembling the real and original being, so are human beings as image bearers of the living God. We are not God but, in some ways, resemble Him. We are capable of having intimate relationships, of articulate speech, of intricate intellection, and so forth. We carry in our persons elements of His being.
The Satanic deception in the Garden (“you will be like God,” having the moral knowledge of and become a peer with Him) is an attack on both the sovereignty of God (as Satan himself had sought to dethrone God) and an attempt to soil human dignity (through Adam and Eve’s acceptance of the lie that they would not bear God’s image if they ate the fruit; they would become Him).
read more at: http://www.canonandculture.com/sexual-madness-and-the-image-of-god/