Doctrine is basically a set of religious beliefs or principles that are held by a group of people. This set of belief is perpetuated by any religious or political group that popularizes them. Doctrine serves no major purpose as such. In the words of Simone Weil, “A doctrine serves no purpose in itself, but it is indispensible to have one if only to avoid being deceived by false doctrines.”
Some religious groups emphasize people to follow the doctrine that they advocate. In case people show refusal to follow the doctrine, they are forced to follow it by forcing them to do so. Masses are made to act against their will to follow doctrines that are baseless and hold no water.
People generally believe that faith is something that one dies for, while a doctrine is something that you kill others for. Doctrines enforced upon people are mass-hated.