The elves have decided your god Talos is false. They (the Thalmor) after fighting a war with the Empire signed a treaty with them that agreed upon peace if they banished the worship of Talos, the Nord god.
The elves have then imprisoned, tortured and executed those who openly worshiped Talos, or anyone they could accuse of such even without proper evidence. Supported by the Empire who have helped the elves capture such Nords.
Is it really to hard to believe that the Nords just want religious freedom? Here is the difference between Ulfric and Hitler. Hitler wanted to commit mass genocide of a religious people (much like the high elves are doing hrrm) Where as Ulfric wants to drive out the heretics who would kill his people for worshiping their own god, and the empire that blindly supports them (at the end of a blade none the less).
The Stormcloaks are more akin to the Braveheart. "William Wallace, a commoner, unites the 13th Century Scots in their battle to overthrow English rule."
Lets replace some words in that.
"Ulfric Stormcloak, a Jarl, unites the Holds of Skyrim in their battle to overthrow Empire rule."
The fact that the Nords want to drive the other races out of Skyrim in no way shape or form relates them to Hitler and honestly I am tired of hearing that comparison. Hitler wanted GENOCIDE. Ulfric has never uttered such a thing. Even though I am sure he wouldn't be sad to see all the elves die because of the jerks they are.