Asoka’s religion presents two prominent aspects, namely, his personal faith in Buddhism, and his desire to propagate a universal Dharma or Law.
His personal religion was Buddhism which he embraced after the Kalinga War.
In his Rock Edict at Maski, he described himself as a Buddha-Sakya.
His Bhabru Rock Edict shows his faith in the Buddhist Trinity, namely, Buddha, Dharma, and Sangha. In his role as a monarch-missionary he did everything possible to advance the cause of Buddhism. According to tradition, it was Sannyasi Upagupta who converted Asoka, and worked as his spiritual guide, and accompanied the Emperor on pilgrimage to Buddhist holy places.
Asoka, however, did not desire to impose his personal religion on his subject population in India. Instead, he propagated a universal religion, acceptable to the people of all creeds and faiths. In his Edicts he inscribed the substance of this universal religion for the knowledge of the masses. This religion or Dharma was not Buddhism. It had no dogma or rigid doctrines. It was like a code of morals, containing the essence of all religions. It was, in fact, like a lesson in ethics, virtues and morality. The purpose of this religion was the elevation of mankind to a higher level of existence.