The paper deals with the rediscovery of ancient scepticism by the Renaissance philosophy, especially that of the 16th century. It examines the conditions of its revitalization as well as the reasons, why the sceptical argument has been so widely applied by the Renaissance philosophers. The most of them used it in defence of their religion against non-believers. Some of he Renaissance fideists were sceptics: they did not want to know, because they did want to believe.