Muslims don't believe that Christians and Jews are infidels. They call Christians and Jews "People of the Book" and consider them to be their spiritual brethren. There are a lot of ugly myths being promoted by people with destructive agendas about what Islam is all about. There are extremist Muslims who may believe such things, but there are extremist Christians and extremist Jews (and extremist Secularists) who also believe some pretty hateful and distructive things about those who don't believe as they do. Extremist Muslims are no more representitive of their religions (or philosophies) overall than are extremist Christians, Jews, and Secularists.