I suppose that God creates the Son just so he can have somebody to save man, whom he knows will fall. He also knows the Son will volunteer to pay the penalty for man's sin, as the Son is in fact shown doing in Bk III after God asks for someone to step forward for the job. God is always running into problems with his omniscience. He knows what will happen and needs no one else to make it happen. But he has to have his huge retinue anyway to pay him homage, and has to give them functions so they won't feel useless. In VI, after the victory, he announces that he'll create the world and man to replace the millions of angels who are now in Hell. These new creatures can someday hope to occupy Heaven itself, he says. He knows this is not to be, so why does he say it? He has an unattractive habit of letting things go on for a while and then saying "Cut" like a movie director. Remember how he leads Adam on, as Adam petitions for a mate? He refuses him a couple of times before breaking in, "Relax, my boy, I was going to give you a woman all along." In God's case, I'm afraid that omniscient equals obnoxious, for me. (It must be tough to know everything that will ever happen, including everything that you yourself will ever do.)
Interesting Book VII factoid: When M. says in line 21, "Half yet remains unsung," he is exactly accurate. This is courtesy of Dr. Bogorad of the University of Vermont. At this news, we feel either relief or dread, depending on our stamina.
And another gift from Dr. B: Tennyson's favorite lines in English poetry were VII, 216-217:
Silence, ye troubl'd waves, and thou Deep, peace,
Said then th' omnific Word, your discord end.
The important topic raised in VII is that of having a proper, not excessive, desire for knowledge. Raphael cautions Adam not to inquire too far. He will tell Adam what he first asks, however, since to know more about God's creation is to be able to praise it more. The problem this doctrine of moderation raises is what is asking too much? In book VIII Raphael says that for Adam to inquire about geocentrism vs. heliocentrism and celestial motions is probing into matters only God has the knowledge of. By why draw the line there? It is totally arbitrary.
Knowledge seems to have two aspects in PL: science and morality. Raphael cautions Adam against delving into science, while God's prohibition against eating from the tree of knowledge appears to have a moral basis. If they eat from the tree, they will then be able to know good only in comparison to the bad (and, I would think, happiness only in comparison to sadness). That seems to be the "hangin" offense for God, while to go after knowledge qua science doesn't get them the death penalty.