I just want to add one more note to what everyone has said:
Remember that the astral is part of the manifest world- because if you can perceive it and give it form, no matter how "abstract" it is still limited by the rules that pertain to it's 'area' or 'region' of perceptibility.
Religion, be it christianity or any other that believes in 'heaven', has taught (indoctrinated) us with the belief that the afterlife is somehow eternal and unchanging, the 'it-all' and 'end-all'- but those of us who have explored many of it's aspects come to realize that it's another way of being, and another way of being is contingent upon rules.
So eternity, that is the idea that 'it always has been' 'outside of timespace', all those things that we associate with the idea of God, is not the astral, as much as the physical world is not either. Why? Because eternity is not contingent upon time and space, and yet, no matter how rarefied, the astral and all the way to the causal planes are, when you get down to the meanings of these words. If it has any rule, if it has any perceptibility by a limited being, it is limited in some way. Does it mean it doesn't exist? No, it means it's not all.
So really, if there is a 'war in heaven', it is most assuredly caused by thought power of whoever is perceiving it and believing in it. And, as someone who has gone to lots of places, some nasty and some nice, it isn't the 'whole picture'. Not even close.
Anyway, that's how I see it.