Derrida stole his ideas from me.
The bastard. But he's dead, and I'm 23. Who wins now, Jacques?
Oh, but maybe it would be useful to add the ol' inward/outward dichotomy to the mix: I totally agree that sacrificing Isaac would be, in an inward sense, constructed no differently than, say, choosing black socks over white ones. What differs in both of these situations is the pressure of inwardness involved in making the choice. Interestingly, the greater the choice the greater the "self" that makes it -- which we also must keep the frailty of language in mind here; it isn't the "self" that pre-exists as some ghostlike quasi-objective entity that somehow "causes" the choice; rather, the "self" is the choice, in a very real sense. The self is freedom. Thus, the greater choice, the greater the "self" (the greater the righteousness in choosing the "right" thing; the greater the defiance in choosing the wrong thing; the greater the weakness in choosing neither). The self is subjectivity that exists only on the playground of objectivity, in this case physicality ("I" exist by virtue of my body).
But, of course, outwardly is where the difference lies -- the outward has relation to the ethical. And while it's true that the ethical is also construed inwardly (you can't find it next to stop signs, or anywhere else in the world) in the sense that it's tied in with the subjectivity of humanity, the religious is outside of the ethical, just as the ethical is outside of the aesthetic. The sort of choice Abraham made was extreme in the sense that it flew in the face of the ethical the most violently; whereas most other "everyday" choices are approximate to the ethical; at the very least they don't contravene the ethical.
Oh, and Derrida's a guy I need to get into. I actually saw like three-fourths of his documentary ("Derrida"), and it was awesome -- partly awesome to see a real philosopher who history will memorize in the flesh, doing all sorts of cool philosophical stuff.