Because, any being that would fit the definition of “God” exists independently of His own creation, and that creation includes time.
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Then what is the definition of God? I ask, because if science is to be held to a high standard, then so should those who criticize it.
Biblical theology as we know it firmly asserts that this is impossible: “Who has been His counselor?”
Goodness can only be learned FROM God. We don’t even know everything that the Sun is (not even whether it flickers on a scale of millennia — a quite possible explanation of the appearance of historical climate changes).