The claim that
is, I think, too strongly worded.
While I haven’t given the issue much thought, there are two pieces of evidence for no-pre-fall-death that come immediately to mind:
- Death is depicted as an evil and punishment for the disobedience of Adam and Eve.
- Paul says death entered the cosmos through one man (Adam).
Of course, we can show that these pieces of evidence are not logically airtight. For instance, in regards to 1, it can be pointed out that this does not entail that death, as evil and punishment, did not exist prior to Adam and Eve. But if conjoined with 2, that explanation looks less plausible.
One might confine this to (textual?) humans, but the problem with this is that when God punishes Adam and Eve he extends the punishment the creation generally (that which was under their dominion). And this fits with other passages of God’s judgment (e.g., Nineveh).
(I think one way to have fruitful discussions here would be to acknowledge strengths and weaknesses in our positions. And it seems to me that the idea that death existed prior to the fall is the weaker position exegetically. If we think the position which is stronger from an internal standpoint is outweighed by far stronger external considerations, fine.)