Religiosity is a synonym of religiousness.
As nouns the difference between religiousness and religiosity
is that religiousness is the quality of being religious; religiosity while religiosity is the quality of being religious or pious, especially when zealous.
religiousness
English
Noun
(-)
The quality of being religious; religiosity
religiosity
English
Noun
(religiosities)
The quality of being religious or pious, especially when zealous.
Synonyms
* devoutness
* pietism
* religiousism
* religiousness
* sanctimoniousness
Derived terms
* religiose