My father's small collection of books consisted mainly of works on polemical theology, and I had read most of them.

Literal

Father's meager book-collection [topic-は] mainly controversial-theology books [from-から] was-composed [but-が], that majority [object-を] had-read.

蔵書 means 'book collection' (蔵 = storehouse + 書 = books). 論争神学 = 'polemical theology.' 成り立つ means 'to consist of / to be composed of.' Dense Sino-Japanese vocabulary throughout. This sentence is from Benjamin Franklin's autobiography.