Halachically speaking (as opposed to a mere Middos Chassidus), is one allowed to own a book or document of another religion? This question can be divided into sub-questions:
1. Would there be a difference if the book/document is only meant for reference, e.g. to quote a passage in an essay?
2. Would there be a difference between books/documents of religions classified as Avodah Zarah [E.g. Hinduism, or possibly Christianity] compared to those of a monotheistic religions, e.g. Islam?
3. Would there be specific differences in how to deal with them as opposed to other books e.g. can they not be displayed publicly because of Maris Ayin?
4. Aside from purchases that directly fund Avodah Zarah, does one have to be concerned about their purchase financing further publications of such material, [e.g. some of the money will be used to print more Bibles or Korans?
Please bring relevant sources. Thanks!
P.S. If your answer would only address 1 of the above 4 questions, please feel free to answer even if you're not sure about the others.