Complex sentence: He condemned the Nazi "worship of race" in a pastoral letter on 29 January 1934, and assumed responsibility for the publication of a pamphlet of essays criticizing the ideology of Nazi ideologist, Alfred Rosenberg, and defending the teachings of the Catholic Church.
Split into simpler sentences: He condemned the Nazi "worship of race" in a pastoral letter on 29 January 1934. He assumed responsibility for the publication of a collection of essays that criticized the Nazi ideologist Alfred Rosenberg and defended the teachings of the Catholic Church.