I have, in fact, read an argument that it is exactly that. Non-Christian religions were, to this author (whose name I have forgotten), all lumped together as "paganism". "Paganism" was not a Christian heresy, and therefore pagans were not to be persecuted but converted. But he managed to justify persecution of both Jews and Muslims because their religions were "incomplete Catholicism", and therefore heretical. Apparantly they were "incomplete Catholicism" because they recognized the God of Abraham but not Christ; he characterized Islam as a "radical simplification" of Catholic doctrine. (Protestants were also heretics, of course, but for different reasons.) Thus, both the Crusades and the medieval persecution of Jews were perfectly justified. This was written by an American Roman Catholic author in the early 1930s, as I recall, and as near as I can tell he was completely serious. :wacko: