User blog comment:Some Argonian Named Kesch/Stormcloak Rebellion: Is Anyone Really Right?/@comment-10207438-20131112051533

The war started after Ulfric and his militia was arrested for liberating Markarth from forsworn rule and returned it to the local Skyrim government, Something the Empire should have done but refused to do, a reward for doing so was free worship of talos, he didn't demand it.

Religion is why the Aldmeri Dominion threatened the empire, Fear is what moved the empire against Ulfric and his men, Ulfric fought back because the government that is supposed to protect the people of the empire was instead fighting them out of fear. Religion is a part of it yes, but it is in no way the real driving force of the war.