On the one hand:
Literalism is a hermeneutical decision (even if implicit) as much as any other approach, and so needs to be defended as much as any other. Literalism is not the default godly way to read the Bible that preserves biblical authority. It is not the “normal” way of reading the Bible that gets a free pass while all others must face the bar of judgment.
So, when someone says, “I don’t read Genesis 1-3 as historical events, and here are the reasons why,” that person is not “denying biblical authority.” That person may be wrong, but that would have to be judged on some basis other than the ultimate conversation-stopper, “You’re denying biblical authority.
On the other hand:
In the long run, however, I am not convinced that all—or even most—of these readers will feel comfortable following Collins. Collins's synthesis requires an ad hoc hybrid "Adam" who was "first man" in the sense of being either a specially chosen hominid or a larger tribe of early hominids (Collins is careful not to commit himself to either option). Although I am sympathetic to Collins's efforts to blaze such a path (and he is not alone), I do not see how such an ad hoc Adam will calm doctrinal waters, since the Westminster Confession of Faith leaves no room for anything other than a first couple read literally from the pages of Genesis and Paul, and therefore entails a clear rejection of evolutionary theory.
Further, this type of hybrid "Adam," clearly driven by the need to account for an evolutionary model, is not the Adam of the biblical authors. Ironically, the desire to protect the Adam of scripture leads Collins (and others) to create an Adam that hardly preserves the biblical portrait. Evolution and a historical Adam cannot be merged by positing an Adam so foreign to the biblical consciousness.
[I'm quoting from a secondary source because the original review is no longer available online.]
When it serves his purpose, Enns belittles the literal interpretation of Gen 1-3. He says denying the historicity of Gen 1-3 is not equivalent to denying biblical authority.
Yet out of the other side of his mouth, he attacks the non-literal interpretation of John Collins. Enns thinks the correct interpretation requires Adam and Eve to literally be the first human beings.
There's no internal consistency to his position. The only point of consistency is that he will say anything, however, contradictory, to attack the Bible and Bible-believing Christians.