Its a difficult one because we need to do something to remove all the Islamist fundamentalists and terrorists that are currently living in UK society and want to bring it under Islamic domination. In the long term education is the best way I think so people don't think like a terrorist, but I also want these people off our streets now and if someone has expressed a view to support killing people using violence should we let them just continue to live in society unmonitored? I think not myself as it's just too dangerous in the UK today. It could be your family they kill next. But obviously it's a double edge sword and can be abused like most things.
One other point is that non terrorists and those who oppose it also look at terrorist content for research purposes. In fact to understand the problem correctly you have to look at it, but does this mean they would be arrested too?
https://steemit.com/politics/@david-michael/islamic-terrorists-walking-freely-amongst-us