Where does “благочестивый” come from?
благочестивый (Russian) comes from Russian чести́ть, from Russian че́сть, from Old Church Slavonic чьсти, from Proto-Slavic čisti, from Proto-Balto-Slavic (s)keistéi, from Proto-Indo-European *(s)kʷéyt-t ~ *(s)kit-ént, from Proto-Indo-European kʷeyt- — to notice; to read.
благочестивый (Russian): devout, pious
Ancestry of “благочестивый”, step by step