Ciriaci then taught ethical philosophy and later fundamental theology at his alma mater of the Pontifical Roman Athenaeum S. Apollinare until 1926.

He entered the Roman Curia as a scrittore of the Apostolic Penitentiary on 21 January 1911, and was promoted to registratore of the same on the following 15 December.

In 1927, Czechoslovakia replaced the holiday of St. John Chrysostom with that of Jan Hus, a heretic in the eyes of the Catholic Church.

[1] On 15 February 1928, Ciriaci was appointed Nuncio to Czechoslovakia and Titular Archbishop of Tarsus by Pope Pius XI.

[4] Ciriaci was named Prefect of the Sacred Congregation of the Council on 20 March 1954,[5] and President of the Pontifical Commission for the Interpretation of the Code of Canon Law on 31 May 1955.