The infallibility of the Church is the belief that the Holy Spirit preserves the Christian Church from errors that would contradict its essential doctrines. It is related to, but not the same as, inde
...one holy Church is to continue forever. The Church is the congregation of saints, in which the Gospel is rightly taught and the Sacraments are rightly administered. –Augsburg Confession
Saint Peter's Basilica facade, Rome, Italy
The magisterium of the Catholic Church is the church's authority or office to give authentic interpretation of the word of God, "whether in its written form or in the form of Tradition". According to
Infallibility of the Church
…in this doctrine long predated this council and was premised on the promises of Jesus to Peter (Mat 16:16–20; Luke 22:32). The ordinary and universal magisterium is considered infallible when it proposes a doctrine that the pope and the bishops dispersed throughout the world who are in communion with the successor…
A part of the Ghent Altarpiece showing three popes (Martin V, Gregory VII and Antipope Alexander V) and other bishops
The magisterium presiding over a council. Shown here is the First Vatican Council, c. 1870.
Tuam Cathedral of the Assumption Sacred Heart Detail 2009 09 14