I feel there is a need for an important point of clarification with regards to Cameron's proposal:
There is some understandable consternation that the Canadian Parliament might be asked to pass a succession amendment that discriminates against Roman Catholics. But there is a misunderstaning based on the media misleadingly reporting that only Roman Catholics would continue to be barred from the throne. Nothing could be further from the truth.
In fact, Cameron proposes to remove EVERY restriction from the succession law that specifically targets Roman Catholics. Under his proposal, heirs will be allowed to marry Roman Catholics (just as they can now marry Jews if they wish). Heirs will even be allowed to grow up as Roman Catholics (just as they can now grow up in the Jewish faith if they wish) without losing their place in the succession.
The religious restriction Cameron proposes to keep is not one that specifically targets Roman Catholicism. It wouldn't be that the monarch simply couldn't be a Roman Catholic, it would be that the monarch would (continue to) have to be an Anglican. Cameron's reason is that the Supreme Governor of the Church of England can't be a Roman Catholic any more than (s)he can be a Mormon, a Baptist, a Lutheran, a Jew, a Muslim, a Buddhist, etc., etc., etc.
The distinction is important because while some 40% of the population of our country is Roman Catholic, some 94% is non-Anglican, so the difference does matter. More importantly, it is imperative that any new succession amendment affirm and strengthen Canada's commitment to the separation of church and state. Requiring the Canadian monarch to be of a specific religious denomination is a clear violation of that principle, even if the monarch plays no further religious role.
Now that Cameron has opened up this can of worms, it will be hard to close it up again. Parliament should use the opportunity to unequivocally secularize the head of state once and for all.