Or, actually, don't read it. Just look at the pictures.
It's pictures she took from a kind of Chick Tracts alternative promoting Halloween themed Christianity*. The art is kind of incredible, and actually, though I hate to pay McEwan a compliment, improved by her photography; the angles and colors and distortion and so on all add up to create a legitimately bizarre aesthetic that I respond to pretty strongly.
McEwan, of course, is too busy being a liberal to appreciate any of this, which is why I recommend that you look at the pictures and skip the text. Her need for outrage (or "contemptuousness" as she generally prefers we pretend it to be) does not allow her to say "The message is a bit silly, but the execution is beautiful." Everything, for a liberal, is goodthinkful or ungoodthinkful, with no other possibilities admissable (with the exception of occasional bouts of excruciating self-righteous ambivalence, as with the soul-wrenching experience of watching movies featuring actors who signed the Free Polanski petition, say).
The nice thing about realizing that all this "culture war" nonsense is just such a crock is that you gain some distance. Look, liberals. This booklet thing is goofy. No child who gets it in their Halloween sack is gonna be convinced by it. They won't even be interested in it except insofar as they'll be pissed off that they can't eat it. So it's in your hands. Sure, make fun of the message. But can't you just stop being terrified of the evil Christianists for long enough to realize that the thing is kind of cool?
After all, if it isn't, why did you take so many pictures of it?
*I'm behind on my internet life, so I'm only getting to Halloween now. Sometime around January I may write something about election day.