A few examples:
Deut. 2: They destroyed towns of King Sihon...killing men, women, and children...leaving no survivors. The context would seem to indicate this was done with God's blessing.
Numbers 31: Instructed by God to take vengeance on the Midianites, Moses gives instructions to kill all boys and non-virgin girls while saving the virgin girls for themselves.
1 Samuel 15: God instructs Saul to destroy the Amalekites, not sparing children and infants.
I think it safe to say that the followers of Jesus are unanimous in considering infanticide to be a gross violation of God's moral code. How does that square with these passages of God-sanctioned infanticide? I don't have a good answer. One unsatisfying answer is that these sorts of things represent an ancient people using God to justify there barbaric actions. I'm not ready to accept what that says about the reliability of scripture. Another answer is "who is the clay to question the potter", God can do what he will regarding life and death. That's not satisfying either, but is probably where I am at this point.
From David Plotz's discussion of 2 Kings chapter 3 in his Blogging the Bible series:
Another appalling war. The bad king of Israel allies with good King Jehoshaphat of Judah to attack the Moabites. The armies end up in the desert without any water. The Israelite king begs Elisha to save them. Elisha says he would let the Israelites die without a second thought, but because he admires Jehoshaphat, he'll help. Elisha then reveals himself to be the Funky Prophet: He can only conjure the power of the Lord when music is playing. A musician is summoned, and Elisha delivers a lifesaving flood of water.
Here's the bad part. Elisha also orders the armies to block every Moabite spring, cover Moabite cropland with stones, and chop down every Moabite fruit tree. They do it, and triumph. But let's hearken back to Deuteronomy, chapter 20, when the Lord establishes laws of war. One of them, explained very carefully, was that you may not cut down enemy orchards. The trees are innocent parties and must be left unmolested. Cutting down fruit trees is a 50-year war crime, ruining the lives of your enemy, as well as their children's and grandchildren's lives. This is presumably why God banned it so emphatically. So, it's confusing and tragic that He encourages it this time. (Alternative theory: Elisha is a false prophet, and these were not God's orders.)
The passage from 2 Kings 3:14-19
14 Elisha said, "As surely as the LORD Almighty lives, whom I serve, if I did not have respect for the presence of Jehoshaphat king of Judah, I would not look at you or even notice you. 15 But now bring me a harpist." While the harpist was playing, the hand of the LORD came upon Elisha 16 and he said, "This is what the LORD says: Make this valley full of ditches. 17 For this is what the LORD says: You will see neither wind nor rain, yet this valley will be filled with water, and you, your cattle and your other animals will drink. 18 This is an easy thing in the eyes of the LORD; he will also hand Moab over to you. 19 You will overthrow every fortified city and every major town. You will cut down every good tree, stop up all the springs, and ruin every good field with stones."
The passage from Deuteronomy 20:10-20
10 When you march up to attack a city, make its people an offer of peace. 11 If they accept and open their gates, all the people in it shall be subject to forced labor and shall work for you. 12 If they refuse to make peace and they engage you in battle, lay siege to that city. 13 When the LORD your God delivers it into your hand, put to the sword all the men in it. 14 As for the women, the children, the livestock and everything else in the city, you may take these as plunder for yourselves. And you may use the plunder the LORD your God gives you from your enemies. 15 This is how you are to treat all the cities that are at a distance from you and do not belong to the nations nearby. 16 However, in the cities of the nations the LORD your God is giving you as an inheritance, do not leave alive anything that breathes. 17 Completely destroy themâ€”the Hittites, Amorites, Canaanites, Perizzites, Hivites and Jebusitesâ€”as the LORD your God has commanded you. 18 Otherwise, they will teach you to follow all the detestable things they do in worshiping their gods, and you will sin against the LORD your God. 19 When you lay siege to a city for a long time, fighting against it to capture it, do not destroy its trees by putting an ax to them, because you can eat their fruit. Do not cut them down. Are the trees of the field people, that you should besiege them? 20 However, you may cut down trees that you know are not fruit trees and use them to build siege works until the city at war with you falls.
What do you think? Why would Elisha encourage them to cut down all the trees in violation of the Deuteronomy passage?
I don't know...when I read the passage from 2 Kings, it isn't obvious to me that Elisha is encouraging or commanding but rather simply predicting. Approval of cutting the trees doesn't seem to be necessarily implicit in his statement...though I would probably assume it but for the Deuteronomy passage.