Born in Dublin, County Dublin, Ireland, in 1930, McDermott studied for the priesthood first with the Dominicans, then at St. Patrick's, Carlow College, completing his studies he was ordained a priest on 5 June 1955 for the Diocese of Birmingham in Alabama, United States.
Hailing from Dublin, County Dublin, Ireland, in 1930, McDermott pursued a career in the priesthood initially with the Dominicans, then at St. Patrick's, Carlow College, culminating in his ordination as a priest on June 5, 1955 for the Diocese of Birmingham in Alabama, United States.