Folks talk a lot about Abraham's willingness to sacrifice his son and they forget the point of the story.
The story is not an end in itself, as people seem to take it here, but is the story that introduces the covenant story, God's bargain with Israel and ó I think ó with the world. Jews mark the Covenant with circumcision because they believe it is a blood bargain. They tie it with their survival as a people. It's very powerful and very primitive all at the same time, whatever your other feelings about the deal may be.
In return for their loyalty, which as Mike pointed out above, has been flawed uneven and silly, not to mention sinful as that of even the most flawed, sinful and silly of non-Jews, God said that he would never again demand the sacrifice of human beings for Him. Other things as well, but that's the one that seems to apply here. God does not ask this of us, the death of two year olds or the death, really, of anybody, if we are to believe the Torah and the books that have entered the Judeo-Christian canon since then. If we kill, we must take responsibility for that ourselves, and we must live with that. No fair blaming it on folks with irrefutable proof that that have a bridge to sell you from here to Salvation if only you kill some two your olds for him.
If you are to believe the Christians, when Jesus died, he died for your willingness to say, No, and to treat that child as you yourself would wish to be treated. As Rabbi Akiva said you should wish to be treated. And as Confucious said you should wish to be treated.
Odds are much much higher that if somebody appears to you, shows absolute proof that they're God, then demands that you should start killing kids, you should start taking your medication again and make another appointment with your therapist.
Really, guys, what are the odds?
About paradoxes, if one looks at Bertrand Russell's Theory of Logical Types, you'll note he offers the rather practical suggestion that paradox seems paradoxical because it is a confusion of levels of meaning, and that once the confusion about level and meta-level is straightened out, the paradox tends to vanish as the linguistic artifact it generally is. "Can God make a stone so heavy He cannot lift it?" for example, suggests, that God may be bound by thought or language at all, while only our ability to conceptualize God is captured here. We are confusing the picture of the thing for the thing itself, sort of an intellectual Cargo Cult, and are trying magically to pretend the manipulations we effect on the language must be the same as those that apply in reality.
If there is a God at all, of course.