Doesn't matter if the Kurds are Sunni or Confucian. This has nothing to do with religion.
The ongoing conflict is not an Arab-Iranian conflict, but a Sunni vs Shiite conflict. The Sunni Arabs are fighting against the Shiite Arabs. So it has everything to do with religion.
It's the continuation of Arab-Persian going back 1500+ years. Kurds are to Iranians as are Bavarians to Germans. Arabs don't like Iran or anything to do with Persian history.
Right now the Iranian revolutionary guards are fighting alongside the Shiite Iraqi army. So that argument is wrong.
There were Arabs who sided with the Persian Empire in ancient history. Mesopotamia (Iraq) was Zoroastrian under the Persian Empire and they were fighting against the initially Pagan and later Islamic Arabs.
This has nothing to do with religion. It's a continuation of a 1500+ year old war between Arabs and Persians. The "Shiite" Arabs are really just the descendents of those Arabs who sided with Persia a long time. Much like Sunni ISIS (Arab) is fighting Sunni Kurds (Kurds who are descendents of Persia)
It's politically correct to write this all off as a religious thing when there's many atheists, people of the same religious branch, Christians, and secularists fighting and they're either picking the side of the Arabs or the Iranians (religion isn't the conflict here).
There's the whole Caliphate thing among ISIS but that's state level rhetoric and probably an element of revanchism to restore an Arab Empire (not sure whom they are blaming the fall of the Arab Empire on but it's probably been scapegoated on Jews, Shiites and Christians. When the real source of the decline was due to the succession crises which occurred in Arab dynasties, in part because of too many male offspring due to multiple wives and dynastic violence was tolerated as well. So you often had good heirs that were murdered by jealous less competent rivals).
