There is a good point that the execution of the Shia Cleric is more about the relationship between Iran [shia] and Saudi Arabia [Sunni].

It comes down to the idea that the governments are using religion as control to further political gains - not the other way around.

This is fundamentally about being the only ones who can continue to supply oil to the rest of the world - not about specific interpretations of Islam. Saudi Arabia is selling their oil so cheaply to keep other emerging markets [Shale Oil] out of the market since it is more expensive to produce. But once Iran is able to sell their oil [but not for US Petrodollars because they are smarter than to become slaves to the World Bank like everyone else] they will be an outright competitor to Saudi Arabia and game over.