The next three chapters of Grudem's Systematic Theology treat the attributes (or characteristics) of God. Chapter 11 deals with God's "incommunicable" attributes, while chapters 12 and 13 deal with God's "communicable" attributes. Incommunicable attributes are aspects of God that he does not share with humanity, like the fact that he is present everywhere (omnipresent). Communicable ones are attributes that he shares with us, like the fact that he is love--we love too. Grudem makes the further claim that "there is no attribute of God that is completely communicable, and there is no attribute of God that is completely incommunicable" (157).
A second section to his introduction talks about the names of God in Scripture. His basic point is that "God made the universe so that it would show forth the excellence of his character" (159). The many images used of God in the Bible are illustrations of God taken from analogies to his character in the creation. "All that Scripture says about God uses anthropomorphic language--that is, language that speaks of God in human terms." These are not wrong or untrue ideas about God, just somewhat figurative or less than fully literal ones. Further, each description of God's attributes in Scripture needs to be understood in the light of the rest of Scripture.
Finally, Grudem clues us into the format by which he will define the incommunicable attributes. He will do so in two parts. The first part of his definition will define the attribute. The second part will balance out what that first part is not meaning to imply. He gives the example of God's unchangeableness. On the one hand, "God is unchanging in his being, perfections, purposes, and promises," but he balances this out with the fact that "God does act, and he acts differently in response to different situations" (160).
Grudem's categorization and descriptions are traditional and are quite acceptable. It is noteworthy, of course, that these categorizations are logical rather than biblical. They are perfectly appropriate attempts to arrange biblical material according to logical groupings that do not derive from anything in the biblical texts themselves. All such categorizations are "extra-biblical," meaning that while they can be built out of biblical content and can fit with biblical material, their organizing principles are not strictly derived from the Bible. Grudem's two part approach to defining God's attributes is also perfectly acceptable.
Grudem is much to be commended for his sense that our talk of God involves a hefty dose of anthropomorphism (or perhaps more accurately, anthropopathism, describing God by way of features of human psyche--anthropomorphism technically has to do with human shape). In theory, Grudem's understanding of God approaches an "incarnational" view, which would see revelation as God largely speaking in the categories of those to whom he reveals himself. Grudem at least accepts a measure of this view when it comes to God's revelation of himself.