He was a teacher and tertiary of the Franciscan order, he was a socio-cultural animator in the area of Bergamo. In 1882 he was appointed as a member of the provincial Commission for the treatment of pellagra, bringing the experience gained by Catholics from Bergamo in the field of prevention of this disease.

On the cooperative side Rezzara established a small credit Bank in 1891 and three years after the social cooperative Bakery of Bergamo. He promoted moreover the catholic female Society of mutual aid. His interest in the “working class issue” made the Holy See indicate him as its representative at the general assembly of delegates of the governments that joined the international Association for the legal protection of workers, held in 1908.

He had an important role within the Church of Bergamo: secretary of the diocesan Direction of the “Opera dei congressi”, of the social economic Union of Italian catholics and in 1909 president of the Association of catholic press. He was elected to the municipal and provincial, favoured the municipalisation of public services. He established a free popular School for adults, created to promote literacy in the valleys of Bergamo.

He collaborated to the creation of some periodicals, among which ”L'Eco di Bergamo” in 1880, the local newspaper still existing today. In politics he carried on the position that approved the participation of Catholics in national political and party life.