English summary: The starting point of this study is the question of the meaning of Christian baptism. There are opposing views: On the one hand Christians interpret baptism as a sign of a spiritual event that is neither caused by the rite, nor necessarily happening during it, but simply pointing to that spiritual event. On the other hand Christians understand baptism - especially with regard to infant baptism - as a sacrament, the effect of which does not ultimately depend on what humans do; on the contrary, God incomprehensibly acts within the person being baptized. The religious historian will be interested in how the culture surrounding the early Christendom, i.e. the ancient Orient and the Greco-Roman world around the Mediterranean, understood and practised religious water rites - such as sprinkling, washing, bathing, drinking, pouring out - for cultic cleansing, expiation, consecration, protection against dangerous powers, healing, sorcery, ordeal and oracle, libation for gods and the dead and whether these customs influenced Christian practices. We do in fact find the same use of water for religious purposes among Christians and non-Christians. However, with regard to the central question of the book, it is even more important to note that the non-Christian water rites were seen as being magical, i.e. they worked if the water possessed the required quality, or was given the right quality through consecration, and the rite was performed according to the prescribed customs. There is much evidence to indicate that Christians increasingly adopted these practices, although theologians did not accept them as magic but rather interpreted them as sacraments or sacramentals. German description: Im Streit um den Sinn der christlichen Taufe und besonders um die Berechtigung der Kindertaufe erscheint es ratsam, diesen archaisch anmutenden Ritus in einem moglichst weitgreifenden religionsgeschichtlichen Zusammenhang zu sehen. Im Kontext der vielfaltigen religiosen Verwendung von Wasser und seiner mythischen Deutung wird deutlich, welche uberragende Rolle dieses Element im Leben der Menschen des Altertums gespielt hat. Es stellt sich die Frage, ob es sich bei den Anwendungen des Wassers um Symbolik oder Magie handelt und ob im christlichen Bereich die Deutung als Sakrament bzw. Sakramentale eine wirkliche Alternative darstellt. Bei einer Bewertung daruber ist zu bedenken, dass die entsprechenden Phanomene auf christlicher und nichtchristlicher Seite eine durchgangige Parallelitat aufweisen.