Forgive me for interjecting... I have been lurking, but just too busy to chime in :-)
If it means anything to you, the thought of killing my own son is, in your words, appalling. I cannot imagine much of anything worse, and I really don't care to try. When we read through that story together, I almost cry. Every time. I cannot imagine having to do something like that.
When I said I would do it (and I would), I am not talking about some voice in my head, or some vision in a dream. I am talking about being fully conscious, and God, I dunno, splitting open rocks and appearing to me, backed by a blinding light or something, booming voice that would shame any Dolby system... maybe like when Galadriel shows herself to Frodo, times about a thousand. My point was, yes, if freakin God actually freakin revealed himself to me, you, or anyone else, you would do whatever he freakin said, because there would be no doubt that it would turn out awesome in the end.
If you ever hear me (or anyone else) talking about killing someone because a voice in their head told them to and they think it was God, you should call the authorities immediately. (They are probably crazy... and if it IS God, you calling the authorities won't make much of a difference, lol)
Carry on.