Faith in Revelations

Catholic faith is more than simply believing that God exists. It's also about believing in whatever it is that He reveals. You can view faith as a sum total of everything that God has revealed over time. This is called the deposit of faith, which are the Church doctrines. Also, you can look at faith as your own personal response to those revealed truths (called assent).

But what are revealed truths? And, furthermore, what do they consist of? A revealed truth is a revelation, or unveiling, by God of certain supernatural truths that humans require for their salvation. The Church believes that most of these "truths" are matters that humans could never have come up with on their own, and required divine intervention by God. An example of this is the idea of a Holy Trinity (the idea that there is only one God, but in three Persons). Humans could never have discovered this on their own, since it is unfathonable to the human mind (even the Church cannot satisfactorily explain how such a Trinity could possibly exist). God had to reveal that one.

There are other truths that humans are capable of coming up with on their own, such as the idea that stealing is sinful and wrong. However, God revealed this anyway, since not everyone understands this idea in the same way. Some revelations are presumed to be obvious to anyone with the use of reason, so people can't claim that they didn't know it was wrong (murder is such an example). But as a result of Original Sin (I'll go into this in a future post, but if you don't know what this is, I would suggest looking it up soon) some applications and distinctions of these truths require some reasoning and thinking (for example, the idea of "false gods"). In order to be fair, God revealed some important truths so that even those who don't devote themselves to reason and study know what it is that He wants.

As for what the revealed truths consist of, the best answer is that it's His Word. The Word of God is his revelation to man. Catholics believe that the Word of God comes in two forms.

The Spoken Word: Called Sacred Tradition,
and
The Written Word: The Bible, or Scripture.

Both of these come from the same source (God) and communicate the same idea-the truth. Catholics (and most Christians, for that matter) believe that His Word reflect what God wants. Since they believe that God consists entirely truth and good, His words are also truthful and full of goodness.