The Teaching Ministry of the Diocesan Bishop. At certain times, the bishops gather in an Ecumenical Council with the Pope, and they teach and proclaim a doctrine that must be accepted with faith because it is divinely revealed. The bishops of the world defined and proclaimed a divinely revealed doctrine at the First Vatican Council (1869-1870). This was when they taught that under certain conditions the Pope himself can proclaim a doctrine that is divinely revealed and must be believed by all. This is known as the dogma of papal infallibility. The entire Church as a body is infallible because the Holy Spirit ensures that she will not err in matters of faith and morals. But this infallibility is exercised in a special way by the Pope and the bishops when together they teach what has been divinely revealed either in the ordinary way of their day-to-day teaching or the extraordinary way of an Ecumenical Council or the Pope himself. The Pope and bishops also together teach truths that flow from Divine Revelation or that are closely related to it. Sometimes they teach these truths as being definitive, which means they must be firmly accepted and held. Sometimes they teach in a less than definitive way, which requires a religious submission of will and mind. United States Conference of Catholic Bishops (USCCB) (2012-04-02). United States Catholic Catechism for Adults (Kindle Locations 2127-2136). United States Conference of Catholic Bishops (USCCB). Kindle Edition.