Unlike his better known brothers As'ad, who became a Protestant, and Faris, who converted to Islam and adopted the name Ahmad, Tannus remained a devout Maronite. He attempted, unsuccessfully, to dissuade As'ad from embracing Protestant teachings; As'ad eventually died in the custody of the Maronite Church for his beliefs. In his career during the 1840s, a decade marked by strife between the Druze and Maronites of Mount Lebanon, Tannus advocated for the Maronite notables.