I too fail to see the issue with a legally conducted gathering with all the necessary permits in place despite what it might look like. A similar gathering of Christians, of whatever persuasion presumably would not raise an eyebrow. We do not know the purpose of said Islamic gathering but if it was simply Friday prayers, then I would posit that it had a political meaning of a territorial nature and that is worrying and I would object to it.
On the subject of Islam, we in the Western world have to believe that almost everything they do publicly has it's roots in Proselytism as the spread of Islam is in it's basic creed much the same way as Christianity was the main thrust of colonial conversions leading to harmonic trade with the West from the 14th Century onwards, pioneered by Catholicism.
Christians in general ceased those direct practices but continue today via charitable Missions and Food Aid, so direct comparisons between the two religious groups is nigh impossible.
What is glaringly obvious, as many people have identified, is the complete lack of a "moderate" Islamic movement, condemning their violent counterparts and actively combating it, as I believe would be the case if radical Christians practiced the same philosophy but it is in our best interests to bear in mind, of course, that to a Middle Eastern moderate Muslim, the armed forces of the Western Powers ARE radical Christians..and thus they can probably sympathise with the quid pro quo or rather abstain from any emotion that counters the rise of Islam.
Finally, and very unlike Christian beliefs and practices, the business of Apostasy (in any way denying their religion) is a death sentence in almost every Muslim country, and to speak out publicly about Islam in any derogatory way, including condemning the extreme violence with which they are associated, brings an instant curse and sword of Damocles over any Muslim family in any country. I am not defending the practice of 'Omerta' but I can empathise with people caught up in the deathly grip of this restrictive & destructive belief set.
How does one counter a religion that is now set up as a perfect Trojan Horse for the militant forces of Radical Islam to exploit? I am not sure that targeting the average Muslim family will gain any more than increasing hatred and dislocation and you sure as hell can't shoot them all. The only strategy that would appear to be effective is the continual removal of the violent men with extreme prejudice, and the targeting of any organised infrastructure.The instant closure of any Mosque associated with radicalism would seem like a no-brainer..
This is a job for Life..and it's worth remembering - Gulf War II, Bush & Bliar did it - this is THEIR legacy...