Dying to Kill Us By ROBERT A. PAPE:

[W]hat nearly all suicide terrorist campaigns have in common is a specific secular and strategic goal: to compel liberal democracies to withdraw military forces from territory that the terrorists consider to be their homeland. Religion is rarely the root cause, although it is often used as a tool by terrorist organizations in recruiting and in other efforts in service of the broader strategic objective.

His solution?

In the end, the best approach for the states under fire is probably to focus on their own domestic security while doing what they can to see that the least militant forces on the terrorists' side build a viable state on their own.

Well, good luck with that.