Evolution means that the creation accounts in the first two chapters of Genesis are wrong. That's not how humans came into being, nor the cattle, nor the creeping things, nor the beasts of the earth, nor the fowl of the air. Evolution could not have produced a single mother and father of all future humans, so there was no Adam and no Eve. No Adam and Eve: no fall. No fall: no need for redemption. No need for redemption: no need for a redeemer. No need for a redeemer: no need for the crucifixion or the resurrection, and no need to believe in that redeemer in order to gain eternal life. And not the slightest reason to believe in eternal life in the first place.
That said, of course there are forms of Christianity which do away with a literal fall from grace, and reinterpret the sacrificial atonement so that no such historical event is required. Nonetheless, the doctrines of fall, sin, atonement, and the last things are closely integrated in traditional Christian theology. Many, many people are committed to forms of Christianity that tend to fall (as it were) apart if the literal Adam and Eve story is no longer accepted. Those people - or large numbers of them - would just as soon abandon Christianity altogether if this set of doctrines no longer holds. They will not cheerfully step over to some kind of thinned-out system of doctrine that involves only a symbolic fall from grace.
Kirby has much else to say in the article, and she says it very well indeed. It's a powerful explication of why evolution and Christianity don't mix well, despite all the efforts of accommodationists. She deserves to be better known and used more frequently at conferences and in books and journals.