Nguyễn Đa was the only prominent leader of the Bửu Sơn Kỳ Hương movement, who was not born in the Hậu Giang area of the Mekong Delta. He arrived from Central Vietnam. Nguyễn Đa was born in Bình Khê district, Qui Nhơn province, which happened to be the birthplace of Nguyễn Huệ, the leader of the Tây Sơn rebellion.
Nguyễn Đa passed the traditional Confucian examinations, most likely in 1845 or the fifth year of the Emperor Thiệu Trị rule. Since he was the candidate who obtained a place in the Cử Nhân examinations hence he was also known as Licentiate Đa, or Cử Đa. Yet instead of pursuing a career of a military officer, sometime in 1867-1868, Nguyễn Đa opted to move to the Seven Mountains area. Presumably he was driven by strong patriotic feelings and planned an attempt to organize anti-French resistance. However, his plans failed to materialize because, at the time, anti-French rebellions suffered a number of casualties and experienced a general downturn in the South. Around this time, Nguyễn Hữu Huân was arrested, Trương Công Định was killed by the French, while Nguyễn Trung Trực found a refuge in the remote areas of western Nam Bộ.
Disillusioned and unable to fight the French, Nguyễn Đa commenced a religious life in the Seven Mountains area where he adhered to the Bửu Sơn Kỳ Hương movement. Yet the French authorities became informed of his religious activities and eventually sent troops to arrest him. Nguyễn Đa had to flee an imminent detention, first to Hà Tiên Province and subsequently to Tà Lơn Mountain, or Chaine des Eléphants, in Cambodia.