Richard Dawkins (from whom the above is taken) certainly writes with the vigor and forthrightness one can appreciate, his forays into the realm of theology and philosophy leave much to be desired. The central issue in a question like the above is whether God has the inherent right to take life. If so, the objection disappears; given his sovereignty over life in general, no justification for the taking of any particular life is even required.
The key here is to recognize God’s relationship to existence in general. If Christianity is true, then God is responsible for the existence of everything other than himself. This means that God’s relationship to the world is not merely one of originating causality, but of conserving causality as well. God is responsible not just for the origination of things; he is also responsible for their current existence.
Thus, my existence, for example, is like a gift that (literally) keeps on giving (to me, that is). I exist at every moment that I do because God, at each of those moments, decides to give me what I did not have before (existence at that moment). Because each moment that I exist I do so in virtue of God’s granting me existence, I am continually being given what I would not otherwise have (existence). Since it is being given to me anew at each successive moment, it is not something I have a right to (just as someone who has been given a gift every day does not thereby have a right to a gift the next day). Since my entire existence (and, thus, my earthly life) is gratuitous, it can be legitimately be withheld from me at any time. The reason for this is because it is never truly mine at all—just as the benefactor can choose not to continue giving gifts to his beneficiary, so too can God choose not to give me existence in the future. But it is important to see that it is not as though God would actually be taking something that was mine, were he to do this. Rather, he would merely be choosing not to give me something that is his. This seems entirely appropriate, and thus God is justified in “taking” life from anyone at anytime for any reason (or for no reason at all, if that were possible).
Because of this, the complaints of Dawkins and those like him are ill-founded wholly apart from any other considerations with respect to the particularities of the relevant Old Testament incidents.