Peruvian prelate Juan Luis Cipriani, Lima’s cardinal archbishop, is dropped from a journalism assignment. El Comercio won’t publish any more of his columns because he cited long passages from Popes Paul VI and Benedict XVI without attribution.
All my teachings come from the pontiffs of the Church. I would constantly have to say: as Pope so and so said…
This is right.
A writer must attribute. Otherwise, one might consider writing book reviews.
An effective writer–or teacher–must have a way to absorb Church teaching from any source, and be able to adapt and reframe in such a way to communicate most effectively to the audience.
Catholic Sensibility 
It is also plagiarism and violation of copyright…equivalent to intellectual stealing.