Having argued that we should not view Islam as essentially intolerant, I now ask, "What if we did?" Or, more generally, what if we identify any particular sect as essentially illiberal and intolerant?
It's all very well for sects A, B, C, and D to draw the conclusion that sect E wants no part of extending liberal tolerance to the others, but that doesn't automatically entail that it's a good idea to start persecuting sect E with fire and the sword. On the contrary, sect E's day-to-day activities are likely to be relatively harmless, and we could not justify criminalising them. The speech from sect E's members will still have value - there are good Millian reasons to extend freedom of speech even to the intolerant (for one thing, it's good for us to have our views challenged). Besides, there will be grey areas; the truth of the matter is that many sects show signs of intolerance, and perhaps none can be thought of as entirely pure if we apply the standards I've been using very strictly. Some public figures, such as Cardinal Pell, live in the grey areas - recall that the Catholic hierarchy gives lip service to a separation of Church and State and claims that its miserable morality - no contraception, no divorce, no stem cell research, no gay rights - has a basis in reason.
It may be that, in practice, there is little more that we should do about sect E, other than complaining and becoming distrustful. However, the overall political circumstances do shift if we come to the conclusion that certain sects (sects that are not so marginal as to merit passing over as irrelevant) are subverting the general ethos of liberal tolerance, or if there is pervasive low-level subversion of that ethos from a variety of sects. I think that, in those circumstances, we'd merely engage in some consciousness raising, but probably take no official action. The consciousness raising might make a member of sect E unelectable as a member of parliament, but there would be no law forbidding her from standing for public office.
But maybe there's more that we could do without abandoning our own values. In Turkey, a political party representing sect E would probably be banned. I don't propose that we'd go so far in Australia or other Western countries, and it probably would not be constitutional in any event.
This conundrum may suggest why it is a good reason to have constitutional provisions to protect us from the sect E's of the world. We may have to extend them a lot of tolerance in practice, even if they haven't signed up to make it mutual, but a strong Bill of Rights could severely limit what they will ever actually achieve.
I'm not sure of the answer to this one, so I'll throw the question open.