I suspect most of those who are familiar with the Old Testament stories and take even a moment to reflect, find some of them worrisome. Among the most significant are the accounts of genocidal warfare practice by the Hebrews under God's direction. Specific examples can be seen the case of the people of Ai (Deuteronomy 20:16-18), the Amalekites (I Samuel 15:3), and the city of Jericho ( Joshua 6:21), where the biblical accounts indicate that the Hebrew army killed every man, woman, and child, thus utterly exterminating their enemies. Even in an "eye for an eye" ethical environment, this seems extreme, though perhaps ruthlessly effective. Ruthlessness is not generally viewed as a human virtue.
Whether one believes these stories to be historically true or not, there remains a powerful moral lesson behind them which, in my opinion, is not the idea that violence in God's name is righteous and promotes moral improvement. Instead, I suspect that these stories point out the stark reality that trying to promote righteousness and God's agenda by killing "bad" people is ineffective, unless all the "bad" people and their potential allies are killed, no exceptions. Going a step further, we might realize that there are elements of unrighteousness in all of us, so that killing our way to righteousness means we all must go.
This same lesson is also born out in the story of the Noahic Flood. Supposedly God sent the flood to rid the world of wickedness by killing everyone but Noah and his family. Did that work? Was sinfulness eliminated from the earth? Definitely not. The reason was that the remaining people were still completely human as ever.
To the extent that Bible believers attach to the idea that sinfulness or human malfeasance can be addressed by killing those we dislike, disagree with, or fear, we force upon these Bible stories a lesson which human history, the Bible itself, and personal experience disallow. Even God could not eliminate human frailty by killing off the unrighteous. He fell eight short of the number he needed to kill.