There are certain infallible truths, revealed truths, in the deposit of the faith of the Church. And the Church can, when need or critical situation arises, declare those truths as contained in the deposit of faith, handed down to it by the Apostolic Church, the sacred scriptures ad the perennial tradition of the Church. Vatican I clearly teaches that the exercise of infallibility is restricted to revealed truths with regard to ‘faith and morals’, and not to be extended to other areas.
According to the teaching of First and Second Vatican Councils, the Church can make infallible doctrinal statements or definitions on faith and morals within the limits of revealed truths, definitions that are binding on all the faithful. In practice such exercise of infallible teahing authority is very seldom, for example, the dogma of the Assumption of Mary.
The dogma of infallibility is connected with the dogma of indefectibility of the Church. There is the sense of faith (sensus fidei). The source of infallibility is the grace of the Holy Spirit.
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