JPII states in Fides et Ratio:
"Faith and reason are like two wings on which the human spirit rises to the contemplation of truth; and God has placed in the human heart a desire to know the truthin a word, to know himselfso that, by knowing and loving God, men and women may also come to the fullness of truth about themselves."
Faith and reason are not incompatible: in fact, reason confirms faith. What the Randians believe is that they can derive ethics explicitly from the natural world. Note what the Catechism states:
"..."Consequently, methodical research in all branches of knowledge, provided it is carried out in a truly scientific manner and does not override moral laws, can never conflict with the faith."
That's the point I was trying to make. Morals come from other places, and are confirmed by reason.
An excellent book on the superiority of Judeo-Christian ethics and their complete compatibility with reason is A Clash of Orthodoxies by Robert George (2001).
Interesting, we may be making progress. You're saying that reason can be used to evaluate competing moral views (e.g. "love your neighbor" versus "kill the Jews"), but is insufficient to develop those views in the first place?