I think I heard it in a podcast once, but I’ve forgotten which one and haven’t been able to track down the source again. The idea was basically this:

The first amendment of the constitution is written so that each part is dependent on the previous parts.

Religion is protected because religion is what you think and believe.

Next speech is protected. It’s listed after religion because what you say is determined by what you think.

Freedom of the press protects what you say widely.

Next the right to assemble is protected because what you write in the press may inspire groups to form to petition the government for change which is the final item.

Because, for centuries, religious sects have spread the idea that beliefs cannot be questioned. Personally, I think this is obviously because if any religion is examined with even a mote of reasonableness and informed inquiry all the religious claims are clearly wrong and based on fairytale-and-wish-thinking.

I disagree that religion should be treated the same way innate qualities like sex or ethnicity are, but it seems clear that until recently, the control religion had over society meant it was rare for people to leave religions like they do now - so religion becomes a proxy for a group, and the group gets persecuted based on their religion.

When people in Northern Ireland burn flags, they’re burning the flag of the Irish Republic, but the people they say they hate are Catholics.

Not all societies do. The US does because many of those who founded it did not want their religious beliefs interfered with by any political powers.

Only Islam get that privilege partly due to French magazine publisher bloody attack years ago and Palestinian guilt. The rest like Buddhism, Taoism, Catholic, Protestant, Sikhism, etc usually don't get much specialty treatment. Take Sikhism that require carrying a Sikh dagger and having long hair, I known many universities blatantly forbid it. The main reason is because a small minority of Muslim devotees tend to be very violent when it comes to their religion "honor". And many Westerners are scared of retaliations.

The foundation of your worldview is more important than your position on a random topic.

And the privileged position of religion comes from a time where the punishment for not following the local approved worldview was anything up to a long torturous death, which didn’t tend to happen for other kinds of beliefs.

Religious belief (faith) is different from normal belief. Normal beliefs are purely internal. The outside world is unaffected by your belief or disbelief in something.

Religious belief on the other hand does have external effects. Your belief / disbelief is directly perceived by God, and God takes actions based on your belief.

In other words, normal belief is a state, religious belief is an action. So, whereas challenging someones normal belief is an act of knowledge sharing, challenging a persons religious belief could get them struck by lightening.

They do as long as it’s not Christianity.