Not exactly true, for example, suicide bombings in Israel has been dominated by shia groups like Hizbullah. Ayatollah Kohemnei has religiously justified the suicide bombers attacking Israel.
On the other hand, Wahabbi/Salafi scholars from Saudi Arabia had actually declared that suicide bombings even if it is attacking Israelis is haram as the Quran explicitly states that suicide is haram.
Another example is the death fatwa on Salman Rushdie was again released by Ayatollah who is a shia cleric and criticized by others including Saudi scholars saying that it is UnIslamic to declare a fatwa of death without a proper trial and allowing the accused to stand in trial.
So its not the religious doctrine itself but the political consequences that results in terrorist acts. After all, the person who assassinated Salman Taseer was assassinated by a Barelvi group that emphasise sufistic beliefs and was then praised for his action.
In short, the worst policy decision a government can make is basing its decision on some ideological blinkers of choosing shia muslims or sufi muslims or some other basis. If you look at how the US manages its foreign policy, it has been looking at its national interests rather than choosing which sect of Muslims because it knows that its a flawed startegy. Every group and every religion has fringe fanatics and that has to be tackled.
If you want to understand the fringe ideology regarding how terrorism emerges, you can check out this link
http://www.defence.pk/forums/curren...wered-questions-case-pakistan.html#post550583
In short, schools of thoughts doesn't decide wether a group religious or otherwise will take to terrorism, but the militant political activism is.