I sympathize with Mr. Bari. I sent him some advice at info@eastlondonmosque.org.uk, under a title similar to "How To Deflect Harassment Regarding the Recent Bombings":
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Expressions of sympathy are nice, but I would suggest that you issue the following statement:
It is the religous duty of all Moslems to assist the authorities, in any way possible, in the apprehension and prosecution of the perpetrators of the London bombings and any other terrorist act.
A sign up in front of the mosque, so that passers-by and the media could see it would likely be quite effective. I would recommend that you also say this in English and Arabic in the Friday sermons.
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Let's see if my advice gets passed on and acted on.
This should be the headline on every newspaper around the world.