 Perić continued his education at the Pontifical Urban University and gained a PhD on 10 December 1971 with the thesis "Meaning of Evangelisation in the Perspective of Anonymous Christianity" under the mentorship of Carlo Molari.He returned to Herzegovina, where he was a parson in Trebinje between 1971 and 1974.Simultaneously, he taught general history and the Greek language at the Humanist Gymnasium "Ruđer Bošković" in Dubrovnik from 1972 until 1974.