[1] On 16 January 1736 he was consecrated metropolitan bishop of Beirut by patriarch Cyril VI Tanas, taking the name of Athanase.
[2] Dahan was taken as coadjutor bishop by his predecessor Maximos II Hakim during his short reign, and after Maximos's death he was elected patriarch by a synod of bishops held on 26 December 1761 at the monastery of Saint Antony, taking the name of Theodosius.
They requested Rome to check the election of Theodosius Dahan, which however was confirmed on 23 September 1763 by the Roman Congregation of Propaganda Fide and on 23 December 1763 by another synod of the Mekite bishops.
[citation needed] Theodosius Dahan was thus formally confirmed by Rome on 23 June 1764 and he received the pallium, sign of the patriarchal authority, on 9 July 1764.
[3] Rome appointed him also as administrator of the Catholics Melkites of Alexandria and Jerusalem, previously ruled by the Custodian of the Holy Land.