Translation:What is the difference between Islam and Christianity?
It seems, Hebrew keeps the consonants, marking the long vowels, in Arabic loan words, especially those of the cultural realm: ג׳יהאד, אינתיפאדה, איסלאם. But in more innocent words like טַיָּרָה (native word is עֲפִיפוֹן kite) or פָלָ֫פֵל it tends to be lost, although some write it טיארה or פלאפל. But with Arabic slang words, like דִּיר בָּ֫לָק (or דיר באלק), i.e. שִׂים לֵב, זְהִירוּת, the Arabic spelling seems to be more prevalent.
Well, the names of religions in Hebrew like נַצְרוּת Christendom and יַהֲדוּת Jewdom are usually used with the article, the same as in German das Christentum and Yiddish דאָס קרי׳סטענטום. What happened here, I suppose, is that when you juxtapose two corresponding nouns which are closely related, you can leave out the definite article: אֲנִי חוֹרֵשׁ שָׁמַ֫יִם וָאַ֫רֶץ כְּדֵי לִמְצוֹת טִפּוּל I am moving heaven and earth to find a treatment, הוּא כּוֹתֵב סֵ֫פֶר עַל דָּת וְיַהֲדוּת he writes a book about religion and Jewry or הַשּׁוֹתֶר יָשִׁיב חֹק וָסֵ֫דֶר the policeman will restore law and order. I suppose this is heavily influenced by European usages of the article, as in German you say was ist der Unterschied zwischen Islam und Christentum? with a zero-article too, .
Let's see if I've got this straight. German and Yiddish (but not English, Italian, Spanish, or any other European language that I'm familiar with) have the quirky habit of both (i) adding articles to proper nouns and (ii) deleting these articles when pairing two nouns together. Modern Hebrew then picked both of these habits up from German and/or Yiddish, most likely Yiddish. And English speakers like me, who would never dream of putting "the" before the name of a religion in the first place, are left scratching our heads.
I'm sorry if that sounds hostile, since I find your explanations extremely helpful. Please keep them up! But to a native English speaker like me, this construction is beyond illogical. It feels downright absurd.
Well, feel free to pity those Slavic speakers who have to learn all the intricacies of the grammatical article from scratch! But are you sure English is not the odd man out amid central Standard European languages? I guess in these cases the Roman languages can drop the article too: Qual è la differenza tra (il) Cristianesimo e (il) Giudaismo? Quelle est la différence entre (le) judaisme et (le) christianisme. But I hope my explanation is water proof. I have found a short summary in the article Nomen ohne Artikel under the point "Doppel- und Mehrfachformen mit und: Wenn zwei Nomen in engen Zusammenhang gebracht und mit und verbunden werden, kann der bestimmte Artikel wegfallen", as you seem to be learning German too.
You may be right. For what it's worth, Google Translate translates "Judaism" and "Christianity" into Italian, Spanish and French with definite articles, but eliminates those articles in Italian and Spanish (but not French!) when asking "What is the difference between Christianity and Judaism?" The Italian and Spanish sentences don't sound right to me without the articles, but that's probably my mistake, not Google's.
English is definitely the odd man out in not applying definite articles to proper nouns like Judaism and Christianity and Islam. In general, Romance languages use definite articles much more than English or German do.
Finally, I'm trying to learn German, but whether I'm actually learning it remains to be seen. German is definitely my 5th best DL language, behind Hebrew and French, way behind Spanish, and miles behind Italian. Italian and Spanish basically make sense to me, aside from the proper use of the subjunctive. French and Hebrew are crazy patchworks of arbitrary rules that I'm starting to get a handle on. And in German I'm like the 4th son at the seder, who doesn't even know enough to ask a question.