"How blessed will be the one who seizes and dashes your little ones against the rock," (Psalm 137:9).
Critics often bring up this verse as an attack on the validity of the Bible. But, does the Bible teach that it is okay to kill children? The answer, of course, is no it doesn't. But we must ask what the Psalmist was saying and why he was saying it.
The context of Psalm 137 is the Babylonian captivity. The Psalmist speaks of the captors tormenting the people of God (vv. 1-3), a promise to remember Jerusalem (vv. 5-6), and a curse against the captors (vv. 7-9).
The Psalmist is in exile and had probably witnessed the atrocities committed against his people, babies included. In the revenge-style that was so common at the time, he wishes the same upon his enemy as a description of their utter destruction. Nowhere does it say that God approves of the Psalmist’s request or that he fulfilled it. Just because it is recorded that the Psalmist wrote the imprecation, doesn’t mean it was approved by God.
This defense of the text is reasonable in that it is completely compatible with the claim that the Bible is simply a work of humans, who are prone to all the imperfections and moral failings of humans. However, if one takes the Bible to offer any sort of moral authority, then this argument shifts the goalposts considerably on counts as Biblical authority. According to this criterion, passages not explicitly stated by God should not be considered authoritative and only requests explicitly fulfilled by God can be considered approved by God. Perhaps, then, the Ten Commandments would qualify as still authoritative but passages such as the Psalms do not. One could no longer take Paul's condemnation of homosexuality as authoritative since that is only Paul's word. One could no longer take Jesus' words as authoritative since those words would not have been stated directly by God. Similarly, one would have to abandon claims for authority about the origin of the universe because this is not stated by God but were descriptions of the origin of the world but not told directly by God.
Moreover, if one accepts this move from the word of God to the word of the Psalmist, then one can apply that to any part of the text. When God tells Gideon to kill the Midianites (in Judges 6-9), that need not imply that God tells Gideon to do that, only that someone says that God said that. If the author of Psalms cannot be trusted to have moral authority, then how can the author of Judges have authoritative knowledge of what God has told people to do?
Continuing directly from the previous paragraphs:
It is worth noting that the Old Testament records many atrocities. The fact is that God allowed people their sinful desires and he worked within their culture, even as he does now, as he permits all kinds of bad things to happen.
In other words, God allows his own followers to commit or advocate atrocities. So, the fact that Psalms advocates killing infants does not mean that it's a good thing to do. It could just be the testimony of one freely advocating inhumane action. Again, this completely undermines the idea that anything in the Bible has any moral authority whatsoever. However, continuing directly:
Nevertheless, God introduced what is called the Apoditic Law (Exodus 21:24): an eye for an eye and a tooth for a tooth. The Apoditic Law was instituted to prevent the increase of blood revenge, a practice where revenge would escalate out of control between two parties. Since the hearts of the fallen are so wicked and the harsh environment and culture produced difficulties for survival, God has a few options to counter their proclivity towards evil. He can run roughshod over their free will and force everyone to obey him, or he could wipe them all out (he had already done this with Noah's flood), or he could work within the situation at hand. In the case of this psalm, and it's Babylonian captivity context, God chose to work with people and through them instead of violating the freedom he had given them and forcing them to act in a manner that he instructs. Therefore, the Psalmist is expressing his curse against Babylon, a natural response to what his people have already suffered.
This reasoning is bizarre. It's saying that God allows the Psalmist to advocate (and presumably commit) murder of infants because the "fallen are so wicked" that extreme measures have to be taken "to counter their proclivity towards evil." This defense does not undermine the authority of the entire Bible, but it is remarkably inhumane. Killing infants is the only way God can counter the evil of the Babylonians. Obviously, this is an absurd defense of killing infants. You cannot counter the parents', or other adults', proclivity towards evil by killing infants. Expressing a curse against someone is understandable, advocating murder of infants is not. This defense fails to establish any humanity or decency on the part of the Bible.
Finally, the defense concludes with the following laughable passage:
Also, the critics need to provide an acceptable, objective moral standard by which they can criticize biblical morality. It is one thing to complain. It is another to offer a justification for the validity of the complaint. By what right and by what objective ethical standard do the critics offer moral condemnation against Biblical morals? This is a serious question that if not answered by the critics, renders the critics’ complaints moot. After all, you must first have a standard against which to measure good and bad and without a standard, no complaints can be legitimately offered.
First, this changes the subject. It shifts from the moral question of the acceptability of an action to the epistemic question of the standards one has to judge that morality. No one needs to enunciate a moral standard in order to criticize the murder of infants which the Psalmist is advocating. All a critic of this passage needs is the claim that killing infants is morally wrong. I can only conclude from this that the authors believe that killing infants (given those circumstances) is morally correct. Otherwise their defense is completely irrelevant to the issue.
Nonetheless, the rest of this passage is still completely off base. There are perfectly acceptable moral standards independently of the Bible. This passage claims that either there are no objective moral standards independently of the Bible or that it is impossible to know those standards. Clearly, this claim is false lest we be unable to attribute goodness (in any meaningful sense) to God, God's choices, or God's commands. We cannot coherently praise God for being good if what it is to be good is defined by the commands God gives. God might just as well command murder (of Midianites or infants?) as command that one not commit murder, and that command would be equally morally good. To paraphrase the Christian philosopher Leibniz, this would make God nothing more than a bully. The Christian needs there to be objective moral facts independently of God in order for it to make sense to praise God for being good. Put one other way: if morality were determined entirely by the Bible, then there would be no reason to be worried about the passage from Psalms at all, there would be no reason to have to explain away the passage. One would simply accept it as obviously correct to kill infants because the Bible says it. We have to explain it away because we know independently of the text that killing infants is wrong.
Now, I do not have a complete theory of morality, but, as I just argued, no one needs a theory of morality to criticize the Psalmist-defender's position. And, although we need not do so in order to criticize the egregious immorality of killing infants, we can at least note some standards. One should not, for example, harm others unless that harm is necessary to prevent greater harm. Since killing infants harms those infants, and the infants are not on the verge of committing genocide (or doing something at least as horrific as the killing of infants), it is obvious that this Psalm advocates a morally wrong action. The Bible must either endorse this, or it cannot be taken as an authority on morality. Hence, we should either reject the Bible as a moral authority or believe that it endorses killing infants.