In the book, Show Them No Mercy: 4 Views on God and Canaanite Genocide, Longman begins his essay, The Case for Spiritual Continuity, as follows:
Modern Americans have a difficult time understanding the mindset of an Islamic "mujahaddin" (holy warrior) like Osama bin Laden. His ideas and rhetoric seem so foreign from those of a modern Western democracy that prides itself on its cultural tolerance. However, Christians who know their Bible should understand exactly what motivates his beliefs and actions. Two Old Testament ideas are analogous to the ideology that fuels bin Laden's passionate ideology: sacred space and "herem" warfare.
Bin Laden's anger toward the West is triggered at least in part by the presence of Westerners in Saudi Arabia. To most Muslims the sacred precincts are limited to areas connected to the holy places at Mecca and Medina. Bin Laden has expanded this idea of sacred space to include the entirety of the peninsula and thus wants all infidels expelled from Saudi Arabia. The analogy with the Old Testament may be found in the sacred precincts surrounding the tabernacle/temple in the Old Testament. The sanctuary was surrounded by circles of holiness that permitted only certain types of people to be admitted into God's presence. This sentiment continued as long as the Second Temple remained in existence; note how riots were set off when some suspected Paul had brought a Gentile into the court of the temple (Acts 21:27-29).
The second Old Testament idea reflected in bin Laden's ideology is herem warfare. Herem may be compared to Islamic "jihad," both of which have been roughly understood as "holy war." America was shocked when innocent civilians were killed in the terrorist acts of September 11, 2001. However, if we are honest readers of the Old Testament, is this so different from the slaughter of Canaanite men, women, and children prisoners of war that we read about in the book of Joshua? (pp. 161-162)
Longman goes ahead in his essay to attempt to justify his God in ordering the genocides. Essentially, he says that all through the Bible God is presented as a warrior God who is doing battle with evil. The final book of the Bible, Revelation (chs. 19-21) reports that God will eventually defeat all evil, including Satan, and reign in perfect holiness for eternity. Therefore, Longman sees no real problem with the fact that in the Old Testament, Yahweh was ordering his people to kill the evil-doers.
In fairness to Longman, he doesn't believe that Christians, or Muslims for that matter, are justified in using these genocidal texts in the Old Testament to kill human beings today. The commands were specific commands given to a specific nation at a specific time and cannot be used by nations or individuals today to justify the same actions. According to Longman, the battles that the church engages in today are spiritual battles not physical ones.
Now, I am sure that many evangelicals would be repulsed by Longman's comparison of the Canaanite genocides to the actions of Osama bin Laden, but I think he is being honest with the biblical text.