One and the same?

     In "Paradise Lost", John Milton manages to combine many different cultures' beliefs about gods, including Christianity, Greek mythology, and Middle Eastern beliefs. This, along with Milton's longevity and eloquence, made it difficult for me to sift through the reading to find any meaning behind it. Although I can't quote a main point to "Paradise Lost", I find it intriguing that Milton would mix so many different cultures within one text. In Milton's long list of gods spanning pages 810-814, he mentions the Cherubim, which adorned the cover of the Ark of the Covenant. This is a reference to Judaism. The listed gods following the Cherubim are from the Middle East, according to the footnote. Enter next the Titans, "Heav'n's firstborn". Milton moves on to discuss Olympus and then the fight at Thebes and Ilium which was "mixed with auxiliary [allied] gods." While this listing of the gods may seem utterly pointless, I believe that Milton was giving a history of the evolution of the gods. Many of the gods discussed were also in the other cultures later mentioned. In the conclusion of Book I, Milton states that "The great Seraphic Lords and Cherubim in close recess and secret conclave sat, a thousand demigods on golden seats, frequent and full." And from the footnote at the end of this line, we gather that Milton meant that the seraphic lords, the cherubim, and the demigods were crowded together, and in full complement. I think this points to the fact that Milton's way of thinking was ahead of his time. He gets at the fact that, because we can see that the gods overlap in other cultures, mayhap the gods are one in the same, none really all that different from the others.
Why is the Archangel considered lost (pg 807 ln 243)? What is Book I setting up? What is the "great consult" mentioned in the last line of Book I on page 819?