Believing in a God, whatever is His name, makes a human stronger. Every believe has its sacred places, with a magnetic effect against people embracing that believe. A spiritual destination is first of all a sacred place, when you feel yourself nearer to your God and some related legends. A spiritual destination is strongly enhanced if hosting the remainings of a saint.
And now a serious question only for the professional traveler: is the pilgrimage a form of tourism or not? Even if you answer “Yes” to this question, you must accept that is a very special one, as fun and entertainment are not at all important things during a pilgrimage.