expression
godless; fearing nothing, not even God
Fixed expression describing someone utterly fearless or irreverent, often with a negative moral connotation. Used attributively to modify a person or action.
彼は神をも恐れぬ所業に手を染めた。
He committed a deed that showed no fear even of God.
Means 'knowing no fear' in general, without the specific religious or moral weight of '神をも恐れぬ'.
A set phrase composed of 神 (god), を (object marker), も (even), and the negative form of 恐れる (to fear). The exact origin is uncertain, but it appears in classical and literary contexts to denote extreme irreverence.