Because they act selectively secular.
We are just exercising our First Amendment rights (assuming we still have those), to voice concern, disdain, and assemble together against such a movie.
History shows you very wrong about this not being a Christian nation -- who told you that anyway, Obama?
I contend that history shows me very right about this not being a Christian nation. There is a difference between a nation largely of Christians free to practice their religion, and a nation that is driven and controlled by religious precepts.
Iran is a Muslim nation - Saudi Arabia is a Muslim nation - the religion and the government are inseparable and indistinguishable.
Separating politics from religion was the very first amendment - topic one in the Bill of Rights.
If you choose not to see a movie just because they choose not to show the destruction of Mecca that is a decision you are free to make, but to me the logic seems rather silly. If you are going to make choices based on religious principles about which movies you see and don’t see - I would think that a movie about the end of the world based on supposed Mayan prophecies would already be off your list.
So, you wouldn’t have protested a movie promoting false Mayan prophecies... But now some of you are upset because it does not actively show Mecca crumbling... Seriously?