Terrorists are quite clear about what they consider victory: conversion of all non-believers to Islam and the subjection of the entire world to sharia law. When Palestinian Arab Islamofascists kidnapped Fox News journalists Steve Centanni and Olaf Wiig, they did not ask them to cancel the Oscars, stump for the Supreme Court appointment of Richard Paez or get them tickets to the Laugh Factory. They forced them to convert to Islam at gunpoint.
This is what Islamofascists do. They aren't shy about their goals. Whatever stops them from achieving those goals is what prevents terrorists from winning. Ethnic profiling helps stop terrorists. Monitoring terrorist phone calls helps stop terrorists. Terrorists aren't all that concerned about gay marriage; they don't win if we pass a Constitutional amendment preventing it.
What about the oft-made argument that if terrorists affect our freedoms, then they have won? Pure sophistry. If our enemies affect our freedoms, they affect our freedoms. We may not like our freedoms being affected. Nonetheless, that has no impact on whether the "terrorists have won." Our enemies do not care whether we allow Robert Mapplethorpe to peddle his tripe on the public dime. They hate us either way.
Only if affecting our freedoms allows our enemies to achieve their actual goals have our enemies won. During WWII, they affected our consumption patterns and civil liberties. We won. During the Vietnam War, they made our counterculture into our mainstream culture. We lost.
If the terrorists achieve global sharia, then they will have won. If they erect a mosque on the ruins of the World Trade Center, then they will have won. They will not stop until they achieve their goals. We must not stop until we have shattered their dreams forever.