Obsequium religiosum is a Latin phrase meaning religious submission or religious assent, particularly in the theology of the Catholic Church.
The Latin term is used in the Latin original document Lumen gentium of the Second Vatican Council regarding the duty of the faithful to give obsequium religiosum (Latin for "religious submission") of will and intellect to certain teachings of the Magisterium of the Church. The Magisterium is a reference to the authoritative teaching body of the Roman Catholic Church.
The phrase appears in Lumen gentium 25a in the following context, here translated as both "religious assent" and "religious submission":
Bishops, teaching in communion with the Roman Pontiff, are to be respected by all as witnesses to divine and Catholic truth. In matters of faith and morals, the bishops speak in the name of Christ and the faithful are to accept their teaching and adhere to it with a religious assent. This religious submission of mind and will must be shown in a special way to the authentic magisterium of the Roman Pontiff, even when he is not speaking ex cathedra; that is, it must be shown in such a way that his supreme magisterium is acknowledged with reverence, the judgments made by him are sincerely adhered to, according to his manifest mind and will. His mind and will in the matter may be known either from the character of the documents, from his frequent repetition of the same doctrine, or from his manner of speaking.
The magisterial teachings of the Catholic Church are gradated according to a "hierarchy of truths". The more central or foundational a truth is in the system of truths proposed by the Church's magisterium, the greater the assent of the will to that "truth" must be. The document Donum Veritatis[1] teaches the following concerning this gradation of assent:
When the Magisterium of the Church makes an infallible pronouncement and solemnly declares that a teaching is found in Revelation, the assent called for is that of theological faith. This kind of adherence is to be given even to the teaching of the ordinary and universal Magisterium when it proposes for belief a teaching of faith as divinely revealed. When the Magisterium proposes "in a definitive way" truths concerning faith and morals, which, even if not divinely revealed, are nevertheless strictly and intimately connected with Revelation, these must be firmly accepted and held. When the Magisterium, not intending to act "definitively", teaches a doctrine to aid a better understanding of Revelation and make explicit its contents, or to recall how some teaching is in conformity with the truths of faith, or finally to guard against ideas that are incompatible with these truths, the response called for is that of the religious submission of will and intellect. This kind of response cannot be simply exterior or disciplinary but must be understood within the logic of faith and under the impulse of obedience to the faith.