Complex sentence: Ducker, Chairman of the Catholic Industrial Affairs Committee, was a former NSW Labour Council Secretary and Minister in the Wran Labor Government, who believed that to be a Catholic, to believe in Catholic social teachings, one must put that belief into action.
Split into simpler sentences: Ducker, Chairman of the Catholic Industrial Affairs Committee, was a former NSW Labour Council Secretary and Minister in the Wran Labor Government. Ducker believed that to be a Catholic, to believe in Catholic social teachings, one must put that belief into action.