Tertullians Aduersus Iudaeos (Against the Jews) is one of the most controversial works of early Christian literature for modern scholarship not only because of its subject matter, which denies the enduring validity of Judaism subsequent to the appearance of Christianity, but also because of the debate surrounding the authenticity of the second half of the work itself. Many believe that the parallels with the third book of Aduersus Marcionem indicate that someone other than Tertullian completed this work by taking material from the latter source. As a result, historical studies of the relationship between Jews and Christians have widely neglected this work.