The Assyrian Church of the East holds that divine revelation is transmitted through both Sacred Scripture and Sacred Tradition. Tradition includes the Apostolic Tradition as embodied in the ancient Councils (especially Nicaea and Constantinople), the consensus of the Fathers (particularly the Syriac fathers), the ancient liturgical texts (especially the Anaphora of Addai and Mari), and the canonical practices of the Church. The church recognizes the authority of the patristic tradition in interpreting Scripture and in defining doctrine.

The church does not accept new doctrines not grounded in Scripture and Apostolic Tradition. However, the Church's living Tradition is understood as the ongoing expression of the Spirit-guided community interpreting and applying the deposit of faith to new contexts. New doctrinal definitions may be issued by ecumenical councils or patriarchal authority, but these must be rooted in Scripture and the ancient Tradition. Private revelations, while valued spiritually, do not add to the deposit of faith.