Moriarty is the son of David Moriarty and Bridget Stokes. He receives his early education in a classical school of his native Diocese of Ardfert and Aghadoe, and later is sent to Boulogne-sur-Mer in northern France. From there he passes to Maynooth College and, after a distinguished course in theology, is elected to the Dunboyne establishment, where he spends two years.
While yet a young priest Moriarty is chosen by the episcopal management of the Irish College in Paris, as vice-president of that institution, a position he occupies for about four years. So satisfactory is his work that, on the death of Father John Hand, he is appointed President of All Hallows College in Dublin, and for years guides, fashions, and makes effective the discipline and teaching of that well known institution. It is during this time he gives evidence of the noble oratory, so chaste, elevated, various and convincing, that has come to be associated with his name.
In 1854 Moriarty is appointed coadjutor, with the right of succession, to the bishopric of Ardfert and Aghadoe, as titular bishop of the Diocese of Antigonea. Two years later he succeeds to his native see. His work as bishop is testified to by several churches and schools, a diocesan college St. Brendan’s College, Killarney in 1860 and many conventual establishments. He finds time to conduct retreats for priests and his addresses which have come down to us under the title “Allocutions to the Clergy” are characterized by profound thought, expressed in an elevated and oratorical style.
In his political views Moriarty runs counter to much of the popular feeling of the time, and is a notable opponent of the Fenian organization, which he denounces strongly, particularly following the uprising in 1867 in his diocese where in an infamous sermon he attacks the Fenian leadership brandishing them criminals, swindlers and God’s heaviest curse. He also declares that “when we look down into the fathomless depth of this infamy of the heads of the Fenian conspiracy, we must acknowledge that eternity is not long enough, nor hell hot enough to punish such miscreants.” Despite this, however, he claims to admire Daniel O’Connell.
While most republicans attempt to work around the hostility of the high clergy of the Roman Church and the fire and brimstone rhetoric of the likes of Moriarty, out of sensitivity to the religious tendencies of the Irish majority, one Fenian by the name of John O’Neill, dares to fire back. O’Neill retorts, “It is better to be in hell with Fionn than in heaven with pale and flimsy angels.”
Moriarty’s principal works are “Allocutions to the Clergy” and two volumes of sermons.
David Moriarty dies on October 1, 1877.