The Slavic language replaces Greek, as a result of the intensive work of the Slav scholars, in Bulgarian church services and in literary life and becomes Bulgaria's official language.

Bulgaria's conversion has a political dimension, for it contributes both to the growth of central authority and to the melding of Bulgars and Slavs into a unified Bulgarian people.

Boris has adopted Greek Orthodox political conceptions, referring to himself as ruler “by the grace of God,” and the new religion provides justification for suppressing those boyars of Bulgar origin who cling to paganism and the political and social order with which it is linked.

After a reign of thirty-six years, Boris, whose faith apparently is deep and genuine, abdicates in 889 and becomes a monk, but he retains the right to take an active part in the government of the state.

His successor,Vladimir-Rasate, is the oldest of Boris-Mihail's sons and possibly the only one of them who had been born before Boris' adoption of Christianity.

According to Emperor Constantine VII Porphyrogenitos, Vladimir had taken part in a Bulgarian invasion of the Serbian lands, predating the Christianization of Bulgaria.

Another Bulgarian-Byzantine war begins in 889, this time over trade rights.