Robert Jordan, the protagonist of For Whom the Bell Tolls, is a young American college instructor of Spanish who has come to Spain to fight for the Loyalists in the Civil War. He has taken this step, presumably, because of a liberal socio-political philosophy and a broad sympathy for the Spanish people. These feelings closely parallel Hemingway's own attitudes toward the Spanish government and people in the period preceding the war.
By the time the novel opens, however, Jordan has become disenchanted. Since his arrival in Spain, he has come face-to-face with the cynicism of those in power, and his reaction to this cynicism has caused the leaders to laugh at his naiveté and to chide him for his "slight political development." Another fact which Jordan has encountered is that most of the common people, regardless of which side they are fighting for, are no longer interested in the war, nor are they very willing to die for the Cause. Having achieved an awareness of these realities, Jordan states clearly in the early pages of the book that he is not a communist, but simply an anti-fascist.
A great deal has been made of the idea that Robert Jordan is not the virile, individualistic hero usually found in Hemingway's writing. To a certain extent, this observation is accurate. Surely the Jordan who existed prior to the opening of the novel, and whom we discover through flashbacks, might have been called a "bleeding-heart liberal" — a highly unusual type of hero for an author of Hemingway's ilk.
The Jordan we see during the actual four-day time span of the novel, however, is a man in transition. Pulled and tugged by ideas of courage and humanity, he moves slowly from a waning belief in the value of the Cause to a new appreciation of the importance of the Individual, and the final impetus to this movement is provided by his love for Maria. In the closing pages of the book, Jordan has done his duty for the Cause and lies injured on the hillside, waiting for the communist cavalry. If, at this point, the Cause retained its original importance to him, he would undoubtedly ignore the temptation to commit suicide in order to do more for "the movement" than just his duty. Instead, he does decide to kill himself, but then changes his mind because only by staying alive can he be of service to those individuals whose safety is important to him.
And so we have a protagonist who, though not precisely the individualistic hero we might expect from Hemingway, is still a man who has progressed to the conclusion that it is less important to "save the world" than it is to save the individuals in it.