I did click the link and as you ask the question, yes I agree Katie Hopkins offers no answers here. The article is well written however, and conveys her opinion. I think it's wrong to use the word extremism though as it contains no call for violence.
She's wrong and she's right. Multiculturalism sometimes works, I have friends of different faiths and we agree to disagree, I don't force my agnostic beliefs on them and vice-versa. The problem arises when religious texts are taken literally and acts of violence are carried out in the belief that one religion is superior to all others and non-believers must die.
If you are born to a religion or adopt it, then the natural belief is that you are right, others are wrong, and you are better than them because of it (otherwise you'd believe whatever they do instead, and I do include agnostism along with all other belief systems). It's simple fact. You can address it by treating everybody equally, regardless of whatever they believe. That's the answer.
Yes, Katie Hopkins clearly has an issue with Sadiq Khan, I don't read the Fail or her writings so don't know the background. On the whole I'm a bit of a fan of Sadiq, however, I read an article where he annoyed me. I think it was the Evening Standard and he was quoted as saying he had no issues with his daughters marrying whoever they wanted (regardless of faith) as long as they were respectful of her (his) faith. Well, that's not his call. He has no say in what his adult daughters do or don't do and particularly he has no say in what his future son-in-law thinks or doesn't think, it's not his choice to make. In a civilised society, religion should be open to debate, open to question, all religions, all beliefs (atheism etc).
Equality is pretty much the answer to everything.