Doctrine

doctrine (from Latin: doctrina, meaning ‘teaching, instruction’) is a codification of beliefs or a body of teachings or instructions, taught principles or positions, as the essence of teachings in a given branch of knowledge or in a belief system. The etymological Greek analogue is ‘catechism’.

Often the word doctrine specifically suggests a body of religious principles as promulgated by a church. Doctrine may also refer to a principle of law, in the common-law traditions, established through a history of past decisions.

wikipedia/en/Doctrine

While closely related, “doctrine” refers to a specific set of beliefs or teachings within a religion, while “theology” is the broader study and analysis of those beliefs, essentially the “study of God” or religious doctrines; so, doctrine is a component of theology, not the same thing as it as a whole. 

Key points:

• Doctrine: A set of established beliefs or teachings within a religion, often considered as core principles. 
• Theology: The academic study of religious beliefs, including analysis and interpretation of doctrines. 

Example: The “doctrine of the Trinity” is a specific belief within Christianity, while “Christian theology” is the broader study of all aspects of Christian faith, including the Trinity.