Paradise Lost by Milton Help Please

 I don't really need much but I have to write a five page paper on this in two weeks before I leave for my career internship program and I've noticed that alot of the characters seem extremely comparable to each other such as God and Satan, Adam and Eve, The Holy Trinity and Satan, Sin and Death; these characters aren't all necessarily opposites of each other but still. I was wondering if any of you guys who have read it can give me some insight as to why Milton might have written it like this. I appreciate any help you guys might have to give