He was born September 21, 1934 in Nam Thành village, Yên Thành district, Nghệ An province, within a family of wealthy Catholic rice farmers ; his father Nguyễn Ðình Long (1906-1976) and several family members were persecuted during the great land reform (1954).
After the reunification of Vietnam (1975), he was among the few professors who did not emigrate and stayed in Dalat University, even though during the next ten years he was not allowed to teach [REF].