This is the 8702nd most frequent Korean word.
가톨릭에
"가톨릭에" means "in Catholicism" or "to Catholicism" depending on context.
In this sentence, '가톨릭에 대한' demonstrates the use of '에' in relation to the topic 'Catholicism', implying the book's subject matter is Catholicism.
저는 가톨릭에 대한 책을 읽고 있어요.
I am reading a book about Catholicism.
Here, '가톨릭에 관심이 많아요' uses '에' to indicate the focus of the interest, Catholicism.
그는 가톨릭에 관심이 많아요.
He is very interested in Catholicism.
In this sentence, '가톨릭에 소속된' uses '에' to express affiliation with the Catholic community.