Nuclear weapons have always been associated with the “end of days”. A repertoire of concepts and images to express this religious dimension can be found in the Bible and in theology. However, it is apparent that these associations do not provide us with a consistent assessment of the phenomenon of “nuclear weapons”. Instead, contrary positions are supported with reference to the same biblical motifs. This is explained by the interrelationships between religious symbols, basic religious attitudes, and personal dispositions. Furthermore, even an identical assessment – such as a rejection of nuclear weapons – can be used to justify different responses. Political and ethical debates about the legitimacy of nuclear weapons and nuclear deterrence have in each case taken account of changes in technological and political environments. During the Cold War, they have moved from the question of a ban in principle to the conditions under which the use of nuclear weapons could be justified. But fundamental skepticism toward attempts to declare weapons of mass destruction compatible with the Just War principles has been reflected not least in the 1983 pastoral letter by the U.S. bishops, “The Challenge of Peace”. While this influential document did not rule out the possible use of nuclear weapons in defense of fundamental values, it opposed nuclear war-fighting and allowed deterrence only under strict conditions. Ultimately, the moral assessment of a phenomenon in accordance with the Church’s social teachings always proceeds from a theological, ethical and social “overall view”. In view of conditions in the world today – including increasing international tensions, terrorism and proliferation risks – the Vatican’s current condemnation of the deterrence policy leaves no doubt that it constitutes a heightened risk to the future of humanity and the planet.