Late Middle English; earliest use found in The Wycliffite Bible (early version). From un- + religiosity, originally after post-classical Latin irreligiositasirreligiosity.
Definition of unreligiosity in US English:
unreligiosity
noun(ˌ)ʌnrɪˌlɪdʒɪˈɒsɪti
rare
Unreligiousness; irreligiousness.
Origin
Late Middle English; earliest use found in The Wycliffite Bible (early version). From un- + religiosity, originally after post-classical Latin irreligiositas irreligiosity.