It is interesting that in Iraq Sunnis and Shias are BOTH accused of sectarian language and threats, but I don´t remember a single powerful or influential Shia leader insult and threat the entire Sunni community. Sure, the Shia leaders use the word Takfiri but this applies only to a small extremely radical portion of the Sunnis. When the (radical) Sunnis, however, speak of the „Rafidha“, again they intentionally target and incriminate ALL Shias.
Even the so called „radical“ or „firebrand“ Shia cleric and leader of the Mahdi army at no time spoke in even a remotely sectarian way as one of the ISIS leaders does here:
http://www.counterpunch.org/2014/06/13/why-the-new-iraq-war-could-be-more-savage-than-the-last/

„the Lord alone who overpowers the Shia. Praise be the Lord who brings terror to their hearts.”“
„Do not concede territory gained to the Shia unless they walk over your dead bodies to retrieve it. March towards Baghdad. Do not let them [the Shia] breath.”
„The Shia are a disgraced people,” he says, accusing them of being polytheists “who worship the dead and stone.”

Interestingly such radicals, call them Salafi or Wahhabi or whatever, consider themselves to be the real, the authentic muslims and to be perfectly familiar with the religion of Islam, but they commit the grave sin of „takfir“ (calling others „unbelievers“) on entirely erroneous grounds.
The Shia „worship“ the dead just as much as football fans „worship“ Lionel Messi or Ronaldo, namely not at all.