The verb corresponding to blasphemy—which means a contemptuous or profane act or utterance against God or another sacred entity—is blaspheme. Its pronunciation (blas-FEEM) can be a little awkward for English speakers as we’re not used to iambic verbs, and this might partially explain why the more natural-sounding blasphemy sometimes appears as a verb, especially in speech.
Blasphemy is about ten times as common as blaspheme, but the verb can be useful—for example:
The past two days, the Red Sox have appeared to abandon the game of baseball, or at least to blaspheme it. [Providence Journal]
This is a warning to those highly sensitive to political blasphemy: Don’t read on. For many, I’m about to blaspheme. [Visalia Times-Delta]
Over and over Jeunet returns to this blasphemed ground, demonstrating the theory and practice of hell. [Washington Post]
After only about two furlongs I was blaspheming under my breath at the sheer audacity of it all. [Guardian]