Tolerance is the least inspiring of virtues: it means putting up with people or ideas that we don’t much like. So Theresa May struck a chord after Saturday’s London Bridge attack when she said that “there is to be frank, far too much tolerance of extremism in our country.”

Correctly exercised, tolerance is a necessary staging post to the higher objectives of trust and integration. But taken to excess, its effects can be toxic. A distinction has to be made between things that must be tolerated and things that must not be tolerated.

Many of us are confused about how to draw this line. Faced with cultural difference, we are unsure which of our own values we are allowed to defend, and which we are supposed to modify or abandon. We see the consequences of that confusion every day, in unrealistic demands for full assimilation or—conversely—the turning of a blind eye to practices that should never be accepted.

“Tolerance does not extend to expressions of religious belief that unjustifiably restrict the rights of others”

Useful guidance may be found in the European Convention of Human Rights—the Council of Europe instrument to which the major parties have all committed post-Brexit. The ECHR is not, as often supposed, a one-eyed assertion of individual freedoms over our responsibility to society. Rather, its half-century of case law, both from the European Court in Strasbourg and under our own Human Rights Act, offers a subtle balancing of the two.

It offers three lessons of primary relevance to the current debate on extremism and integration.

First, confidence in setting limits. The European Court reminds us that democracy is founded on tolerance—but also on pluralism and broad-mindedness. So everyone has an absolute right to believe what they like, to change their beliefs, and to share them with like-minded people. But tolerance does not extend to expressions of religious belief that unjustifiably restrict the rights of others.

That is so whether you are a Christian who wants his child to be beaten at private school, a Hindu who seeks to rely on the sacred status of a bullock to avoid the legal consequences of a TB diagnosis, or a political…

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