There's not much to be said that hasn't been said already really. This topic has been done to death on here before and will be done many more times in the future unfortunately, because this problem will only get worse, not better.
There's no way of stopping it completely but it can be slowed down imo. Terrorist organisations like IS rely on the people of the Western world to recruit new members as much as they rely on themselves.
They attack innocent people, as they did last night in Paris. Then they announce they did it in the name of Islam and wait for the inevitable Islamaphobia that sweeps the world. People start to say things like, "Islam is supposed to be the religion of peace apparently, what a load of bollocks. Islamic people are just following their religion to the word of what their bible equivalent tells them." So, not only are Muslims falling for terrorist propaganda, we are too. In turn it creates hatred and division within communities. People, not everyone, but some people tar all Muslims with the same brush.
Most of ther people that commit these atrocities on western soil are the people that have been raised here. We can help stop them becoming a terrorist.
When a Muslim from one of our communities is approached by a radicalist hoping for a new member, the potential new member needs to make a choice. He or she can either think - (a) You know what, everything this radicalist is telling me is right, these people hate our religion, I've seen it. They've treated me like a terrorist even though I had done nothing wrong. They've tarred me with the same brush as everyone that commits terrorist acts and treated me like shit and made me feel alienated in what is my own country. If that's what they think of me then that's what I'll be. They treat me like shit so I don't care any more. Fuck them.
(b) You know what, this guy is talking shit, the people in my community have been good to me. They are good people who understand that the word of our religion is being misused by dickheads that want to kill people for no reason. They haven't tarred me with the same brush as terrorists and I refuse to kill people that have welcomed me.
A bit idealistic I know but you have to start somewhere and I can't think of any other ways to help, can you?