Pat Condell makes a career out of taking the piss. Nothing wrong with that in itself, many comedians do so, but constantly sniping at people of religion wears a bit thin after a while.
Regarding Sadiq Khan, I doubt many are worried about his faith, he's a moderate man and the British tend to go for moderates when it comes to religion, it's when people bang on about their religion all the time they are put off; he is a Londoner so he understands the concerns of Londoners. I like what I have seen so far but he has yet to prove himself.