The name of the enemy
The actual name of the group is this:
Ash-Shâm is actually an archaic word for Syria as a region, which historically refers to a larger area than the present-day country of Syria (the Arabic name of the modern country of Syria is Sûriyâ), so some writers translate it into English as "the Levant" -- hence ISIL, the other commonly-used acronym for the group.
The letters I've underlined in red above are the first letters of each of the four words (the reason they don't look like they're at the beginning of the words is that in Arabic the definite article al- is written joined to the word following it). The first letter of 'Irâq is actually a "throat" consonant with no European equivalent, often represented in transliteration by an apostrophe. When you combine the four letters to form an Arabic-script acronym, you get this:
Using Dâ'ish in English would have some advantages. It would end the confusion between ISIS and ISIL, which are just acronyms for different translations of the same Arabic name and not really different names at all. Abandoning ISIS would end the sullying of a perfectly good ancient Egyptian goddess and perhaps stop idiocies like this. And it would put us on the same page with the Arabic-, Kurdish-, and Persian-speaking people who are fighting against the group. We get along fine, after all, calling al-Qâ'idah by its Arabic name, however badly mispronounced (it translates as "the base", but few Americans even know that). To say Dâ'ish correctly, drawl out the first vowel a bit (DAA-ish) and try to glide from the "a" to the "i" without any consonant in between (or a glottal stop, to approximate the Persian pronunciation), and you'll get pretty close. It's the name I'll be using from now on.