Heresiology
（重定向自Heresiologist）
In theology or the history of religion heresiology is the study of heresy. Heresiographical works were common in both Medieval Christianity and Islam.
Heresiology developed as a part of the development of orthodoxy in the Roman/Byzantine Church. Church scholars studied and documented the teachings of various Christian sects in order to clearly distinguish between those they accepted as orthodox and those they rejected as heretical. Other Christian communions developed their own competing heresiological traditions as well.