In a way that shows irreverence or disrespect toward God or sacred things; with blasphemy.
From blasphemous (adjective) plus -ly adverb suffix. Shows how English creates adverbs by adding -ly to adjectives, one of the language's most productive patterns.
Medieval writers used this adverb to describe the worst kind of speech—it became so loaded with meaning that even saying something 'blasphemously' was considered dangerous!
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