Johann Andreas Eisenmenger
Even The Jewish Encyclopedia states that for nineteen years Eisenmenger studied rabbinical literature assisted by Jews, first in Heidelberg and afterward in Frankfort-on-the-Main, pretending that he desired to be converted to Judaism. The prince elector of the Palatinate, for who he worked, took great interest in the book, appointing Eisenmenger professor of Oriental languages at the University of Heidelberg. However, the court Jew Samuel Oppenheimer and others gained an order of confiscation from the emperor. There was also Roman Catholic influence at work, as Eisenmenger was accused of anti-Catholic tendencies. Jews offered to pay Eisenmenger, if he would suppress his work. The discussions led to no result. Eisenmenger died suddenly of apoplexy in 1704. His heir published the book at his own expense in 1711, stating that it was printed outside the empire to avoid the censorship.
The book became widely used by critics of Judaism. Critics of the book have often not criticized the accuracy of the translations, but instead claimed that the quotes are taken out of context and misleadingly interpreted.
See also the articles on Criticism of the Talmud (copy of deleted Wikipedia article) (especially the section "Johann Andreas Eisenmenger") and the article on Judaism.