The concern for absolutes in ethics asserts that ethical teachings or understandings exist that are in fact valid for all times, for all people, for everywhere. Absolutes are universals. When someone claims that a particular activity was right in ancient times, i.e., herem the practice of holy war where the inhabitants of whole cities are slaughtered, but wrong now, they are in fact denying and abandoning the concept that absolute values are found in Scripture. One could just as easily argue the opposite as many in fact do, that what was prohibited in ancient times is acceptable now.
Back in 2001 after the tragedy of the towers I introduced discussions to reveal how difficult it should be to assess such horror among those who take the Book of Joshua quite literally. I started by citing the evidence of the ancient custom of herem, translated "utterly destroy" (NRSV). The Israelites wanted to follow the practices of other nations (1 Sam. 8:5). They did not wish to be unique and they were not unique. This was also true for the herem for it was also practiced by the neighbors that surrounded them as ancient texts prove:
And Chemosh said to me, "Go, take Nebo from Israel!" So I went by night and fought against it from the break of dawn until noon, taking it and slaying all, seven thousand men, boys, women, girls, and maid-servants, for I had devoted them to destruction for the (god) Ashtar-Chemosh. Moabite Stone (14-17) ANET3 (1969):320
The practice of herem is idealized in the Torah but especially in the legislation of Deuteronomy (Num. 21:2-3; Deut. 7:2, 12:2, 20:16-20, but save the fruit trees) and up to the time of David may have been a customary element of battle. It forms the very heart of the contents of the Book of Joshua where the practice of "holy extermination" is a central religious idea of the conquest stories (Joshua 2:10; 6:21; 8:26; 10:28,35,37,39,40; 11:11,12,20,21). It is the code by which Samuel is told to have functioned and judged Saul (1 Sam. 15: 1-33). Such a view would be blatant triumphalism and parochialism for one to condemn what Moab practiced in honor of Chemosh (since a false god cannot express his will since he cannot speak) while blessing what Israel practiced in honor of YHWH (because one asserts that that the God who can speak) and Father of Jesus Christ (the source of the teachings contained in the Sermon on the Mount) commanded the wholesale annihilation of Israel’s enemies.
How can they who give their blessing to the slaughter of Joshua then judge the actions of those who seized the jets and crashed them into the towers in honor of Allah? I emphatically reject in these cases that deity (Chemosh, Yahweh, or Allah) is the source of oracles commanding such pillage. Humanity is the source of such hatred. And since this is the case I can easily believe that humans will commit great atrocities in the name and on behalf of any deity they confess to follow. History is full of such examples, including unfortunately many committed by Christians.