Many Christians are puzzled about why atheists cannot seem to let go of the Crusades. Why must we continue to bring up these atrocities from the relatively remote past, they wonder, and use the atrocities of their ancestors against them today? It hardly seems fair. One might even be tempted to use American slavery as an example to illustrate how little sense it makes to blame a people for what their distant relatives did. And yet, I'll be taking a very different position here and arguing that atheists must not let go of the Crusades.To paraphrase the common maxim, we who do not remember the past are doomed to repeat it. We must remember the Crusades, the various periods of the Inquisition , the Salem witch trials, the Satanic ritual abuse scare in the 1980's, and recent revelations about the Family . We must remember these grotesque episodes just as we must never forget the Holocaust, Jonestown, or Heaven's Gate. We remember them because we cannot allow them to be repeated.And yet, there is more to it than maintaining these memories out of any noble cause. No, we must remember because our very survival depends on it. Atheists remember many of these periods because there are enough of us, at least in the U.S., who go through our daily lives feeling that another such period could be right around the corner.We lived 8 years under a Christian extremist presidency, and we are too suspect of human nature to conclude with absolute certainty that we'll never see a President Huckabee . It could happen. We have heard again and again how our Christian neighbors feel about us and what some of them would like to do to us to relax completely.We have seen a Christian extremist presence infiltrate our military, at least one of our modern political parties, and countless wealthy corporations. The consolidation of political power, military strength, and massive wealth into Christian extremist hands is something that should terrify every atheist. We know what can happen because we have seen it again and again throughout history.Those of us who live in hotbeds of Christian extremism often feel that we are a step closer to the nightmare that others have the luxury of pretending is solely in our past. "Never forget" is our cry, and we are not about to abandon it. Celebrate progress where one finds it, but never forget. Far too much is at stake.