Analogia entis

The rule of faith (Latin: regula fidei) or analogy of faith (analogia fidei) is a phrase rooted in the Apostle Paul's admonition to the Christians in Rome in the Epistle to the Romans 12:6, which says, "We have different gifts, according to the grace given us. If a man's gift is prophesying, let him use it in proportion to his faith." (NIV, 1984) The last phrase, "in proportion to his faith" is in Greek κατὰ ἀναλογίαν τῆς πίστεως ("analogy of faith"). In Romans 12:6 this refers to one of three possible ideas: the body of Christian teachings, the person's belief and response to the grace of God, or to the type of faith that can move mountains. This phrase in Romans 12 becomes the root for later usage of the term by such Early Christian writers as Tertullian. Tertullian links it to the core set of Christian teachings, i.e.:

Let our "seeking," therefore be in that which is our own, and from those who are our own, and concerning that which is our own, – that, and only that, which can become an object of inquiry without impairing the rule of faith.

The rule of faith is the name given to the ultimate authority or standard in religious belief, such as the Word of God (Dei verbum) as contained in Sacred Scripture and Divine-Apostolic Tradition, as among Catholics; theoria, as among the Eastern Orthodox; the Bible alone doctrine, as among some Protestants; the Wesleyan Quadrilateral of faith, which held that Sacred Scripture, tradition, reason, and experience, as among other Protestants; and reason alone, as among Rationalist philosophers. As a standard for adherence to orthodoxy, rule of faith originally referred to the Old Roman Symbol, which was an earlier and shorter version of the Apostles' Creed and other later statements of faith. As a historical standard for adherence to orthodoxy, rule of faith may also refer to other statements of faith including the Nicene Creed, Athanasian Creed, Augsburg Confession, Articles of Dort, Westminster Confession and others, the inner light of the spirit, as among mystics.

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