In July 1777 he became archbishop of Aleppo; anyway due to the persecution by the Greek Orthodox Church of Antioch he dwelt for most of his life in Zouk Mikael, Lebanon.
Returned to Syria he was highly esteemed by Patriarch Agapius II Matar and played an important role in the 1806 Melkite Catholic Church's synod in Qarqafe (or Karkafeh).
Consequently, in his 1799 book Réponse de Mgr Germanos Adam, évêque d'Alep et de ses environs à l'ouvrage intitulé: Voix des Pères missionaires consultés par S. S. le patriarche Mar-Ignace-Michel, patriarche syrien d'Antioche (1), le tout bienheureux, et par Mgr Ignace, le très respectable évêque de Beyrouth,[4] Adam supported the doctrine of Conciliarism, and stated that the papal authority was more honorary than actual.
Adam's doctrine was confirmed by the 1806 Melkite Synod of Qarqafe, which acts were signed also by Patriarch Joseph Tyen and by Aloisio Gandolfi, the Apostolic Legate.
In 1812 a formal condemnation of the Jansenist and Gallican doctrine, issued by Propaganda Fide, was signed by all the Eastern Catholic Churches.