The First Amendment reads..... "Congress shall make no law respecting an establishment of religion".........
Those are the ONLY restrictions in the US Constitution over the role of religion in the nation.....it is, of course, a precaution against the government installing a national religion with special priviledges as England did with the Anglican Church....where the Head of State is also the leader of the State Church......
All the other crap Judges have piled on top of that simple requirement for separation of church and state is extra-constitutional judge-made law, and is incorrect in the unadultered light of the Bill of Rights.......
On that note, I actually see an advantage to the establishment of an official religion. I do not profess the Christian Faith myself, but I've read that if British schools teach religious studies, the Christian Faith must be included along with at least one other Faith of the school's choosing. It does provide an advantage in ensuring that though one is free to adopt the religion of his choosing (the UK has just as much religious freedom as the US), that there is at least one common Faith all are familiar with, providing a foundation for dialog between various religious communities. It also helps to alleviate fears among the population in reassuring them of the position of the majority religion in their society, thus providing stability.
This of course could apply to any Faith. If for example, Iran had adopted Islam a its state religion along the same lines as the UK has done with the Christian Faith, it would have provided the same benefits. Unfortunately, Iran has gone way too far. I think Britain has found a nice balance between freedom of religion and a state religion ensuring cultural stability.
I don't agree with the Canadian position though of denying that Canada is a religious state and then turning around and granting a particular religious community a distinct and unfair advantage through separate schools and official religious statutory holidays. In the UK, there is no denying or pretending that there is no official state religion, yet the official state religion does not allow for separate public schools as such, but rather simply that if religious studies are taught that the Christian Faith must be included.
It may appear unfair on the surface, but it does provide cultural stability. By having an official state religion, for example, Britain has managed to avoid the culture wars raging in the US, where there is no clearly defined religious culture in the state, thus raising fears among the majority population.
Again, this is not about promoting this or that religion. If Iran adopted a similar policy ot Britain's but for Islam, I'd support that too, as long as I'm free to practice my own Faith and am not forced to adopt the Christian, Muslim or other Faith, but merely that I must learn it and be familiar with it as a part of a well rounded cultural education so as to be familiar with the dominant religious influences in the country.
