Firstly I asked myself, who was this letter by, I initially thought it must either be a wind-up or possibly from the group who proposed to convert the former Pineapple pub into a mosque, but then as I read on I wasn't too sure.
Assuming the letter is genuine and from a Stalybridge local unconnected with the mosque proposal, the individual responsible deserves pity. If they really believe that going to a mosque is on par with going to church or a temple they really want to probe a little deeper.
As for loving "how multicultural the UK is", now that probably is genuine. Stalybridge is still overwhelmingly populated by indigenous Britons and if this person thinks multiculturalism means exchanging pleasantries with an immigrant shopkeeper or going for chicken tikka massala on a Saturday night, they would be bitterly disappointed when they discovered the true reality of multiculturalism.
It is a curious fact that many of the loudest proponents of multiculturalism such as say Billy Bragg who can be found living in hideously white Dorset or Lilly Allen in the far from multicultural Cotswolds have one thing in common and that is they believe multiculturalism is wonderful, but just not not for them. I suppose their principled stand could be compared to that of a supporter of nuclear energy who waxes lyrical about this wonderful source of clean and reliable energy, as long as the plants which produces nuclear energy are as far away from them as them as conceivably possible.
What I would suggest to "name and address supplied" in relation to their letter regarding the mosque and their vision of a multicultural utopia is why not up-sticks and move to Glodwick, Longsight, Rusholme, Moss Side (which has some lovely period properties) or even Cheetham Hill and live the dream, but here's a word of advice from someone who knows; the reality is often greatly different than the utopian dream.