There is no doubt that Ashoka's personal religion was Buddhism. In his Bhabru edict he says he had full faith in Buddha, Dhamma and Sangha. He showed respect to all sects and faiths and believed in using among ethical and moral values of all sects. In Rock Edict VII he says all seeks desire both self control and purity of mind. In Rock Edict XII he pronounces his policy of equal respect to all religious sects more clearly.
The Dhamma as explained in Ashoka's edicts is not a religion or a religious system but a moral law, a common code of conduct or an ethical order. In Pillar Edict II Ashoka himself puts the question what is Dhamma? Then he enumerates two basic attributes or constituents of Dhamma: less evil and many good deeds. He says such evils as rage, cruelty, anger, pride and envy are to be avoided and many good deeds like kindness, liberty, truthfulness, gentleness, selfcontrol, purity of heart, attachment to morality, inner and outer purity etc are to be pursued vigorously. Ashoka established hospitals for humans and animals and made liberal donations to the Brahmans and ascetics of different religious sects
He erected rest houses, caused wells to be dug and trees to be planted along the roads. Ashoka took for the propagation of Buddhism. He conducted Dharamyatras and instructed his officials to do the same. He appointed special class of officials called Dharamahamatras whose sole responsibility was to propagate Dhamma among the people. Ashoka sent missions to foreign countries also to propagate dhamma. His missionaries went to western Asia, Egypt and Eastern Europe. Of the Foreign kings whose kingdoms thus received the message of Buddhism five are mentioned in the inscriptions of Ashoka namely Antiochus, Syria and Western Asia, Ptolemy Philadelphus of Egypt, Antigonus Gonatas of Macedonia, Megas of Cyrene and Alexander of Epirus. Ashoka even sent his son Mahendra and daughter Sanghamitra to propagate Buddhism in Srilanka.