It's not too hard to think of words that are characteristically used in English almost exclusively by Muslims - salat, namaz, wudu, shahada, masjid... There are even a few such words that aren't borrowings from Arabic or Urdu: circumambulation comes to mind. It is much more difficult, at least for me, to think of characteristics of "Islamic English" that go beyond the lexicon.
I was recently struck, however, by the expression "upon the truth". Searching for "upon the truth" yields plenty of mainstream English examples like "hit upon the truth", "lay hold upon the truth", "an essay upon the truth of the Christian religion"... However, searching for "be upon the truth", "are upon the truth", "is upon the truth", etc. yields a very different picture. Suddenly almost every single search result is specifically Islamic:
- "a) Hindering from the path of Allah, b) and confusing the person into believing that he is upon the truth" (Anonymous, Mission Islam
- "Either all of them are upon the truth which is impossible since truth is not open to contradictory differences or one of them is upon the truth" (Shaykh Haytham Al-Haddad in Muslim Matters)
- "This is because ibn 'Arabee held that all pagans and idol-worshippers were upon the truth since Allah is in his view everything" (translated from Shaykh Muhammad Ibn Rabee Ibn Haadee Al-Madkhalee's The Reality of Sufism in Light of the Qur’aan and Sunnah)
- "who do I follow among all those who claim to be upon the truth?" (Zahra Anjum in the International Islamic Publishing House blog)
You get the idea. The rare exceptions, like "their ultimate dependence is upon the truth", reflect quite a different construction, as the inanimate subject shows. In English, referring to people or groups being "upon the truth" appears to be unique to Islamic discourse (perhaps even to some genres thereof; most of the hits seem to have a vaguely Salafi vibe).
While this construction uses only well-known English vocabulary, it literally translates the Arabic expression على الحق ʕalā l-ḥaqq "on the truth/right". Within Arabic, this expression has a bit of an archaic ring to it, but is familiar from a number of hadith, e.g:
فَجَاءَ عُمَرُ فَقَالَ أَلَسْنَا عَلَى الْحَقِّ وَهُمْ عَلَى الْبَاطِلِ
At that time `Umar came (to the Prophet) and said, "Aren't we on the right (path) and they (pagans) in the wrong?" (Bukhari 65.365)
Being "upon the truth" is thus a calque into Islamic English from Arabic. No doubt a wider investigation would reveal other such cases.