At the Jemaran, Zeitlian studied under such noted leaders of the First Armenian Republic (1918–1920) as Levon Shant, Nigol Aghpalian, Simon Vratsian, and Garo Sassouni.
During his tenure, a high school and boarding facilities were added to the institution and its Alumni Association was formed.
In 1965, Sarkis Zeitlian moved with his family from Anjar to Beirut and became the editor of the ARF organ Aztag.
In the dire circumstances of Lebanon, despite sustaining material losses and fully aware of the many dangers he faces as an ARF political and community leader and the editor of the ARF Bureau organ, Sarkis Zeitlian remained on the political forefront in Lebanon.
In 1978, during one of the most dangerous and chaotic stages of the civil war, when secret service organizations of foreign countries were operating freely, and especially when journalists were being killed or abducted for exercising free speech, Sarkis Zeitlian became Editor-in-Chief of Aztag Shapatoriag-Troshag, the ARF Bureau organ, set the policy and ideological guidelines of the ARF media worldwide, and took on other party responsibilities.
He stressed the importance of the fundamentally national-Armenian basis of the ARF ideology, despite the presence of a loud socialist internationalist faction within the party.