[P-Marlowe]

What is a papal declaration?

You tell me. Is Catholic doctrine determined by papal declaration or by consensus of some committee?

[annalex]

Catholic doctrine is determined by the Magisterium, which consists of the bishops of the Church acting in consensus. Councils of the Church are milestones in this effort. The Pope guides the process visibly as the Holy Ghost inspires it. The pope, very occasionally, makes pronouncements that are infallible; most and for many popes all of the writing that they author is held in high regard but is not infallible. The popes typically express they pastoral guidance in written form through "encyclicals", which address a particular issue in a relatively concise form.

The doctrine has the immovable dogmata of the Church at its core. Nothing in the doctrine can be self-contradictory or contradict the scripture (although certainly interpretations of the scripture some individuals make may contradict the interpretation that is doctrinal).

There is generally a hierarchy of regard given particular opinions, where the teaching of the apostles, the fathers of the early Church, the doctors of the Church such as St. Thomas Aquinas, and the popes are given precedence, in order of their historicity and apostolicity. The process is guided by the Holy Ghost at all times. Individual Church fathers, today or in the past, may have expressed opinions outside of the doctrine. Only consensus patris as a whole is considered authoritative.

The Catechism of the Catholic Church is a definitive guide to the Cathoic teaching.

I will post a collection on salvation of the Hindus and such shortly. As always, thank you for your questions.