Hypernormalization is the phenomena of people continuing to behave as if society is still functional even though it's clearly not. It was first observed in the Soviet Union during its deterioration and collapse, but is also seen in the US, such as when people expect they can call local law enforcement to deescalate a local dispute, even though police are now notorious for escalating to violence more quickly than ordinary civilians.
Anyway, it's a thing.
They'd get it as soon as the other Christians decided they needed to worship on Saturdays instead of Sundays. Wars are fought over trivial deets like that.
In fact, our Constitutional framers had to deal with bloody conflict between the CoE and Catholics, each of whom would declare the other illegal (and punishable by forced conversion or death) whenever the faith of the high king would change. It was messy.
I think all our white Christian nationalist folk are going to learn this the hard way if a state religion is ever established in the US, that in fact, they are not aligned with the state faith.