suprisingly good
I was suprised at how good it was. You mentioned it was your first flash, so my expectations weren't high, but I thought you did very well for your experience. The part where Satan was being banished to hell was downright good. It was extremely expressive and it set the tone very well. That said, I think it would have been improved if it had more of a point. Satan taking over heaven is all well and good, but it was just an armies clashing sort of thing. For this to really work you either need better action, or a better plot. I think you have real potential for either and just need to work at it and keep practicing.
Oh, and as far as the concept goes, I was a little bugged that Satan ended up winning. Not that I'm a serious Christian- quite the contrary. I just think it ended badly. For one, it would add to Satan's depressing wretched/downcast thing he had going on. It also makes it seem unklikely and insignificant that Satan was ever thrown down in the first place. Why didn't he whup God in the beginning?
I hope to see more of your work in the future.