That's what the Pentagon believes. This article in the Christian Science Monitor lays out the details, but the big picture is easy to grasp. It's dumb to say that Al Queda and Muslim terrorists attack the U.S. because of our freedoms. They attack the U.S. because of what our government does to Muslim people.
I think it was Osama Bin Laden in his latest videotape that said something like "you might notice that we haven't been attacking Sweden." Sweden has just as many (if not more) freedoms than we do, but they aren't engaged in what many Muslims consider to be another Great Crusade against them.
So, whether our foreign policy is wise and humane or arrogant, oil-fueled, stupid and harmful is up for debate. But we should recognize that the foreign policy, and not 'our way of life' is what motivates those who try to attack and kill us every single day.