Ok...It seems to me that you would basically take it for granted that "The Fall" occurred, based on your interpretation of Christian Scripture. I have no problem with that. However, it has to be noted that it is a belief that has its basis in faith, and faith alone. But, i get the feeling that you realise and accept that.
From my view, i give it to you, in that i regard such a scenario as a possibility. Of course, i also regard the possibility that i and all around me was created a second ago, complete with memories and a "false" history, with equal merit. Don't get me wrong, i'm not poo-pooing your belief; i'm just saying that either is a possibility.
The possibilities are endless and even science acknowledges its inability to test for many of them.
There are, however, implications to all these possibilities, including that of "The Fall". From what i've read in the thread so far, i take it that you accept that current knowledge (based, as you put it, on a "fallen" reality) points to evolution being factual. It also points to the universe being billions of years old. For these reasons you will not dispute either. Yet, if this is the case, and it is the fall that resulted in a reality that corresponds to Old Earth and Evolution, then would that not mean that the christian God had caused it to happen, since He brought about the fall (not saying He was responsible for it, just that He made it happen)?
The major implication of this is that the christian God has been extremely deceitful. Since it is He that brought about the fall, which resulted in us seeing the world as it seems. What sort of absolutely moral God would do that (based, of course, on our subjective morality)?
If that is the case then Christianity as a religion would be pointless; how can one worship a God that would not follow the ideals that are expected of His worshippers?
"The good Christian should beware the mathematician and all those who make empty prophecies. The danger already exists that the mathematicians have made a covenant with the devil to darken the spirit and to confine man in the bonds of hell." - St. Augustine