We speak of God as perfect because He is infinite and self-existent (Q4), but knowledge is also perfection and God embodies all perfections by his very essence. Therefore, God is (not has) perfect knowledge of all things. As He is infinite, and as His knowledge is infinite, He is infinite comprehensive knowledge.
As his very essence is this knowledge, He is not limited to knowing himself, but as promoted by his infiniteness He knows everything about anything realized or not. His knowledge is not and did not grow to perfection but is always was, simultaneously, unlike human knowledge. Since He is act and is knowledge, these two work in unison truly to have ordered all creation simply by his approval. His knowledge has no limitations, once again, and so this is furthered to the goodness and evil in all things for He knows what one thing and another lacks. Even further, as God’s knowledge is infinite, He will know the infinite thoughts of all created beings, angels, human, and other. As the Satan had to approach God to tempt Job, so is a perfect example of his “approbation.”
Finally, God’s knowledge transcends all things. For he does not merely know everything, He knows the very “is” of all things; their essence. As eternity is changeless as present, this knowledge (God) will not change either.
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