Islamic teachings in a common and famous division is divided into three sections of beliefs, ethics and jurisprudence. In the field of jurisprudence with a historical background, ijtihad scientific work has always been considered and considere however, in the two fields of doctrinal and moral knowledge, despite their great importance and impact on the guidance, growth, perfection and happiness of human beings and society, ijtihad and mujtahid scientific efforts have received much. less attention after defining the concept and purpose of ijtihad in doctrinal teachings, this article seeks to prove the necessity of ijtihad and deep inferential work in the field of doctrinal teachings by stating three types of Quranic arguments, narration and reason and after mentioning many narrative and rational arguments, it is concluded that it is very necessary and essential that in the doctrinal teachings, accurate and deep ijtihad and inferential efforts, such as ijtihad in jurisprudence, be done properly and adequately.