I'm sure if asked, Hitler would have said "1+1=2". Does that mean 1+1 does not equal 2?
Dismissing a claim simply because you don't agree with the source in toto is a logical fallacy. It's entirely possible that a source, even if it's erroneous in some areas (which of course I don't believe that about Catholicism) but even if it is erroneous in some areas, that doesn't mean it's erroneous in all.
no, if you are looking for a catholic answer to a question, you would go to a catholic source. However if you were to go to another outside source you would probably find a different answer...