blaspheme (v.)

"to speak impiously or irreverently of God and sacred things," mid-14c., from Old French blasfemer "to blaspheme" (14c., Modern French blasphémer), from Church Latin blasphemare (which in Late Latin also meant "revile, reproach," hence blame (v.)), from Greek blasphemein "to speak lightly or amiss of sacred things, to slander," from blasphemos "evil-speaking" (see blasphemy). A classical reintroduction in English after the original word, taken from vernacular Old French, had been worn down and sense-shifted to blame. Related: Blasphemed; blasphemer; blaspheming.