When Non-Christians (or even Christians) ask Christians if God can do/know/be/have something, often the response is “of course He does because He is God.” Or the phrase might be in the form of a negative “if God did not do/know/be/have something then He would not be God.” This is a form of the logical fallacy of Begging the Question (assuming a premise without evidence). This is also a wholesale rejection of Jewish theology.
Hebrew theology starts with the premise that Yahweh is God. Yahweh’s characteristics are determined through the examination of Yahweh’s thoughts and deeds. Only after a wide array of Yahweh’s thoughts and actions are examined does Hebrew thought assign predicates to God. God is not powerful “because He is God” but because Yahweh created the universe, freed Israel from Egypt, parted the Red Sea, and many more power acts. The power acts are surveyed and a general attribute is established.
Greek theology starts with the premise that god is defined by a series of attributes. These attributes are deduced through logical proofs. The attributes are usually based on quantifying god. How much power does god have: “all power”. Where is god: “nowhere” or “everywhere”. God is described through negative attributes (attributes that distance from creation) rather than qualifying attributes (attributes in common with creation).
In Greek theology, any action or act by god is then filtered through these attributes. If omnipotence declares that god can do anything, then all acts are interpreted in this light. If God frees Israel from Egypt, that is because god can do anything. If immutability declares that god does not change, then any event that appears like a change must be reinterpreted. In Genesis 6, God does not repent of His own actions of making man, but is instead said to grieve over an event He already knew would happen.
Colin E. Gunton speaks the differences between Greek and Hebrew thought in his Act and Being:
Greeks appear to stress a theology of divine being, Hebrews of divine action… there is a tendency to identify the divine attributes by a list of ‘omni’s’ and negatives – omnipotent, omniscience, omnipresent, infinite, eternal, and the rest – and then paste on to them conceptions of divine actions
Old Testament scholar Walter Brueggemann speaks on this in Theology of the Old Testament:
Israel’s characteristic adjectival vocabulary about Yahweh is completely lacking in terms that have dominated classical theology, such as omnipotent, omniscient, omnipresent. This sharp contrast suggested that classical theology, insofar as it is dominated by such interpretive categories and such concerns, is engaged in issues that are not crucial for Israel’s testimony about Yahweh and are in fact quite remote from Israel’s primary utterance…
The Old Testament, in its discernment of Yahweh, is relentlessly committed to the recognition that all of reality, including the reality of Yahweh, is relational, relative to the life and destiny of Israel. And the God of Israel has no propensity to be otherwise than related to Israel.
When Christians object with the phrase “… then He would not be God” they are engulfed in Greek mode of thought (for a famous author doing this, see AW Pink). These Christians are assuming attributes that make God the God-being. These attributes, as shown from the diversity of religions in the world, are highly speculative and arbitrary. It also functions as a rejection of the Bible, which is a highly Jewish document bred in Jewish theological thought.
The Bible does not attempt to reinterpret the text in light of overriding attributes. Thus, while God is described as being longsuffering and having infinite mercy (1Ch 16:34; Psa 106:1, 107:1, 118:1, 136:1), the text allows God to show a lack of mercy to King Saul (whose repentance was rejected by God), Pharaoh (who was singled out for destruction), and Ananias/Sapphira (who committed an infraction and was not given a chance to repent), to name a few.
This is an important point to make. A reader cannot just copy and paste various phrases about God that are found throughout the Bible and then form a Systematic Theology from those phrases. Those phrases, in themselves, are usually generalities formed with counter-examples in plain view. To make those phrases absolute and then deny the counter-examples would be proverbially “putting the cart before the horse”.
It is a great mistake to engage in Greek theology when the Jewish theological tradition stands in stark contrast. The Bible tells people God’s character through God’s acts and thoughts. The Bible does not allow overriding principles of what God “should be” to override the narrative or testimony about God. Any argument premised in the fashion that “God would cease to be God, if true” should be rejected as pagan reasoning.