The nature and value of the religious priesthood have often been questioned, including after Vatican II. John Paul II, however, claims that the religious priest ‘reproduces in his life the fullness of the mystery of Christ’. Examining Aquinas’s understanding of Christ’s total self-sacrifice provides a model that explains how. In this article, I present a Christological and Thomistic approach to the question by identifying Christ as a religious priest, highlighting one of Aquinas’s patristic sources (St Gregory the Great) and one of his greatest spiritual interpreters of modern times (Bl Columba Marmion). Because of his grace of headship, Christ contains all the perfections found in his members. The perfection of Christ’s priestly and religious life consists in his total sacrifice of himself to the Father out of love. Christ firmly fixed his will to offer himself from the moment of the Incarnation. By vowing to follow the counsels, religious priests imitate the fixity of Christ’s will to offer himself as a total self-holocaust. This conclusion allows me to propose that Christ is the religious priest, which has several theological and pastoral implications.