The answer to finding these terrorists might be easier than they think, after all Muslims believe there is a magic man in the sky and anyone who believes that is a bit daft regardless. We all know there is no Allah and Mohammed was not his final messenger, but they believe it so why not exploit it?

Just ask them if they are terrorists, and if they say no say "ok you swear on the honour of Allah that you are not a terrorist or have terrorist thoughts"? Swearing to god and the holy bible or whatever doesn't mean shit to most people because most people know that it's all bullshit and don't take it seriously, but I don't think a terrorist would be able to lie on the name of Allah. Say "if you're lying now you also agree that Allah is shite and Mohammad fucked animals", and there's no way they could lie even to protect their own necks, so when they come clean arrest them and it's one less terrorist on the streets.