Just saying that it seems "always unjust to kill a child" is not enough—we would have to show that even the cases in normal human experience in which someone has to do this (e.g. the horrible, but all too frequent, situation in which a father is forced to decide in the labor room of a hospital between the life of his child OR the life of his wife...many/most bio-medical ethics experts will side with killing the child, to save the life of the mother/wife) the actions of the father would be "unjust" as well. For, if we even allow ONE EXCEPTION to this "always unjust" statement, we open up the possibility that whatever ethical principle allowed that exception MIGHT ALSO BE operative in other/this case, and we also open up the possibility that there may be other principles that would allow such an action (e.g. mercy killing--refugees that kill their own small children to keep them from being tortured, enslaved, mutilated, and/or then killed horribly by their tormentors).
What this means is that an individual’s personal moral intuitions, if they run counter to moral intuitions of other experts and peers, may need further analysis and qualification, before they could function plausibly in constructing a logical argument of God's non-existence.
In other words, the argument that I THINK someone might make about this might look like the following:
1. The biblical God CANNOT commit any unjust act (Authority: theological tradition)
2. God ordered the killing of children (Authority: biblical text)
3. The killing of children can never be a 'just' act, regardless of competing ethical demands in a given situation. (Authority: someone’s personal moral intuition)
4. God, therefore , ordered an 'unjust act'. (authority: substitution of terms)
5. The ordering of an 'unjust act' is itself an 'unjust act' (authority: not sure--this is somewhat controversial in ethical theory, but I will grant it here for the purposes of illustration)
6. The biblical God, therefore, committed an unjust act. (authority: substitution of terms)
7. Therefore, the biblical God CAN commit an unjust act. (authority: from the actual to the possible)
And at this point we would have a clear logical contradiction between statement #1 and #7, and presumably could conclude that that God could not exist (since our concept of this God contained a 'hard contradiction').
But notice the problem--the whole thing stands or falls on the accuracy of the personal moral intuition in Step 3. It there is no reason to believe it applies WITHOUT EXCEPTION, then our attempt at constructing a hard contradiction this way fails. I have already mentioned one case in which exceptional circumstances are generally considered by experts to apply (i.e., the labor room), and one other case that has a high degree of probability for being another (i.e., the refugee camp), and there might be more that could be advanced (some of which I will offer below). This, of course, puts the ball back in the individual’s court to do one of two things: (1) show that these exceptions do NOT hold--and that the father who chooses to terminate the baby's life, so that his wife doesn't die has committed a horrible, unjustified, and culpable crime at the level of deliberate murder; or (2) show that although there ARE legitimate exceptions, there could not be any valid exceptions that would be operative in our biblical case.
But in any event, someone would still have much, much work to do, to be able to even offer the 'it is a contradiction' position as an argument. Without such work, this objection is simple assertion, unsubstantiated opinion (e.g, 'hunch'?), or emotional statement.
http://www.rationalchristianity.net/genocide.html#today
