He continued his studies at the Interdiocese Preparatory Seminary in Zagreb, Croatia (Croatian: Interdijecezanska srednja škola za spremanje svećenika v Zagrebu), taking his leaving exam in 1962.

[1][2] Stres' education was then put on hold for two years because of mandatory military service in the Yugoslav People's Army; he was stationed in Ohrid, SR Macedonia.

[1] The same year, Stres returned to the Ljubljana faculty as graduate student and also as an assistant instructor at the Department of Philosophy; on 1 October 1974 he defended his doctoral thesis Development of the Marxist Understanding of Religion in Postwar Yugoslavia (Slovene: Razvoj marksističnega pojmovanja religije v povojni Jugoslaviji), thereby obtaining his doctorate in theology.

[1] On 7 April 2006, Pope Benedict XVI reorganized the Roman Catholic Church in Slovenia.

[3] On 31 January 2009, Stres was appointed coadjutor archbishop of Maribor and at the same time he became apostolic administrator of Celje.

[1] On 31 July 2013, Stres stepped down as the archbishop after the request by the Holy See due to his partial responsibility for the financial crisis of the Maribor Archdiocese.

[5] Stres is a member of the Slovenian Catholic Girl Guides and Boy Scouts Association.