 The Constitution of Bulgaria defines it as a secular state with guaranteed religious freedom , but designates Orthodoxy as a " traditional " religion . The Bulgarian Orthodox Church gained autocephalous status in 927 AD , and currently has 12 dioceses and over 2 @,@ 000 priests . More than three @-@ quarters of Bulgarians subscribe to Eastern Orthodoxy . Sunni Muslims are the second @-@ largest community and constitute 10 per cent of the religious makeup , although a majority of them do not pray and find the use of Islamic veils in schools unacceptable . Less than three per cent are affiliated with other religions , 11 @.@ 8 per cent do not self @-@ identify with a religion and 21 @.@ 8 per cent refused to state their beliefs . 
