The correct answers would be precept, creed or axiom.
The word doctrine means a principle that directs something. It could be a principle or doctrine in church or policy in government.
For instance, the doctrine or precepts that are followed by the clergy in a determined religion. They have to do this and behave like that to following their doctrine. In the case of politics, the Monro doctrine in the United States that stated "America for the Americans."
